Composition of vinyl ether group-containing (meth) acrylic acid ester and production method thereof

ABSTRACT

It is an object of the present invention to provide a vinyl ether group-containing (meth) acrylic ester, which has both radical polymerizability and cation polymerizability, improved in storage stability and stability in handling without impairing its polymerizability or, in other words, provide a stabilized vinyl ether group-containing (meth) acrylic ester. Another object is to provide a method of producing a stabilized vinyl ether group-containing (meth) acrylic ester composition. A further object is to provide a method of stably handing, a method of economically and stably producing and a method of purifying a vinyl ether group-containing (meth) acrylic ester. A vinyl ether group-containing (meth) acrylic ester composition which comprises a radical polymerization inhibitor and a vinyl ether group-containing (meth) acrylic ester represented by the following general formula (1): 
       CH2═CR1-COO—R2-O—CH—CH—R3   (1) 
     in the formula, R1 represents a hydrogen atom or a methyl group, R2 represents an organic residue and R3 represents a hydrogen atom or an organic residue.

CROSS REFERENCE

This is a divisional of application Ser. No. 11/552,486, filed Oct. 24,2006, which claims benefit to application Ser. No. 09/982,861, filedOct. 22, 2001 which claims benefit to Japanese Application No.2000-322575, filed Oct. 23, 2000. The entire disclosures of the priorapplications are considered part of the disclosure of this divisionalapplication and are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a vinyl ether group-containing (meth)acrylic ester composition and a method of producing the same as well asto a method of handling, a method of producing and a method of purifyinga vinyl ether group-containing (meth) acrylic ester.

More particularly, it relates to a composition comprising a vinyl ethergroup-containing (meth) acrylic ester having different kinds ofpolymerizable groups within the molecule and capable of being easilyhomopolymerized or copolymerized with some other polymerizable compoundsby means of heat, ultraviolet rays, radiant rays, electron beams,radical polymerization initiators or acids, etc., and a method ofproducing the same as well as to a method of handling, a method ofproducing and a method of purifying said vinyl ether group-containing(meth) acrylic ester.

BACKGROUND ART

Vinyl ether group-containing (meth) acrylic esters have different kindsof polymerizable groups, namely radical- and anion-polymerizable(meth)acryloyl groups and cation-polymerizable vinyl ether groups,within molecules and, therefore, they are useful compounds which can beused in a wide range of industrial use as raw materials in medicinalchemicals and agrochemicals, as synthetic intermediates and further aspolymerizable materials.

A number of studies have been made on the radical polymerizability andcation polymerizability of vinyl ether group-containing (meth) acrylicesters. However, because of their easy radical polymerizability andcation polymerizability, vinyl ether group-containing (meth) acrylicesters are poor in stability, which leads to impurity formation,peroxide formation and polymerization during storage or handlingthereof, hence they can hardly be said to be put into fully practicaluse.

For methods of producing vinyl ether group-containing (meth) acrylicesters, there are known the method comprising subjecting (meth) acrylicacids and hydroxyl group-containing vinyl ethers to esterification(method A), the method comprising subjecting (meth) acrylic halides andhydroxyl group-containing vinyl ethers to esterification (method B), themethod comprising subjecting (meth) acrylic anhydrides and hydroxylgroup-containing vinyl ethers to esterification (method C), and themethod comprising subjecting (meth) acrylic esters and hydroxylgroup-containing vinyl ethers to transesterification (method D), and thelike. The above esters can also be produced by the method comprisingsubjecting (meth) acrylic acids and halogen-containing vinyl ethers toesterification (method E) and by the method comprising subjecting (meth)acrylic acidalkali (or alkaline earth) metal salts andhalogen-containing vinyl ethers to esterification (method F).

Of these production methods, those methods using halogen-containingvinyl ethers as starting materials cause the formation of an equimolaramount of byproduct salts. Therefore, those production methods usinghydroxyl group-containing vinyl ethers as starting materials aresuitable from the industrial viewpoint. Since, however, hydroxylgroup-containing vinyl ethers are generally produced by the additionreaction of diol to acetylene (the so-called Reppe reaction) or by thegaseous phase dehydration reaction of diol-monoalkylene oxide adduct, anumber of impurities are formed as byproducts. Since these impuritieshave properties such that are close in boiling point to hydroxylgroup-containing vinyl ethers, form azeotropic compositions therewithand are close in polarity thereto, for instance, a complicatedpurification is required for the complete isolation to obtain purehydroxyl group-containing vinyl ethers and cost of production of purehydroxyl group-containing vinyl ethers is increased thereby.Consequently, the vinyl ether group-containing (meth) acrylic estersproduced by using such hydroxyl group-containing vinyl ethers asstarting materials become expensive. Thus, the advent of methods ofproducing vinyl ether group-containing (meth) acrylic esters at low costusing hydroxyl group-containing vinyl ethers as starting materials isawaited.

Another problem is that since vinyl ether group-containing (meth)acrylic esters, when produced by any of the methods (A) to (F),decompose during the process of production thereof, leading to impurityformation, peroxide formation and polymerization, it is impossible tostably produce them.

The method of producing vinyl ether group-containing (meth) acrylicesters which comprises subjecting (meth) acrylic ester and a hydroxylgroup-containing vinyl ethers to transesterification is advantageousfrom the industrial viewpoint since it does not use any expensive orhazardous raw materials. However, it has the problem that the yields ofvinyl ether group-containing (meth) acrylic esters is decreased bypolymerization occurring in the reaction system. Further, there isanother problem that peroxide formation due to the excess of molecularoxygen and impurity formation due to decomposition. There is a furtherproblem that since the starting material hydroxyl group-containing vinylether, and the product vinyl ether group-containing (meth) acrylic estereach has a vinyl ether group, side reactions such as polymerization ofthe vinyl ether groups of the products and starting materials as causedby (meth) acrylic acid formed in trace amounts due to water occurring inthe system and isomerization of the starting material hydroxylgroup-containing vinyl ether to the corresponding2-substituted-1,3-dioxo compound occur.

For the method of purifying the vinyl ether group-containing (meth)acrylic esters produced by such methods as mentioned above, there areknown the techniques of extraction, washing with water, evaporation,distillation and column chromatography, etc. However, because of theeasy radical polymerizability and cation polymerizability of vinyl ethergroup-containing (meth) acrylic esters, polymerization occurs in theprocess of purification and, further, impurity formation may easilyoccur as a result of decomposition. Accordingly, vinyl ethergroup-containing (meth) acrylic esters can hardly be said to beproducible stably from the industrial viewpoint. The quality and storagestability problems of the product obtained still remain unsolved. Thus,there is room for investigation with a view to prevent the formation ofimpurities as a result of polymerization and decomposition of vinylether group-containing (meth) acrylic esters in the stages of storage,handling, production and purification thereof and thus render such vinylether group-containing (meth) acrylic esters fully practical forindustrial use.

The present invention has been made in view of the above-mentioned stateof the art. Accordingly, it is an object of the present invention toprovide vinyl ether group-containing (meth) acrylic esters, which hasboth radical polymerizability and cation polymerizability, improved instorage stability and stability in handling without impairing itspolymerizability or, in other words, provide stabilized vinyl ethergroup-containing (meth) acrylic esters. Another object is to providemethods of producing stabilized vinylether group-containing (meth)acrylic ester compositions. A further object is to provide methods ofstably handing, methods of economically and stably producing and methodsof purifying such vinyl ether group-containing (meth) acrylic esters.

SUMMARY OF THE INVENTION

The present inventors made investigations in various ways in search formeans of improving the stability of vinyl ether group-containing (meth)acrylic esters, which have both radical polymerizability and cationpolymerizability and, as a result, found that by causing a radicalpolymerization inhibitor to coexist with vinyl ether group-containing(meth) acrylic esters, it is possible to improve the stability of vinylether group-containing (meth) acrylic esters while preventing thepolymerization thereof during storage or handling without impairingpolymerizability of vinyl ether group-containing (meth) acrylic esters.They also found that when a basic compound is further caused to coexiston that occasion, the stability of vinyl ether group-containing (meth)acrylic esters can be more improved. Thus, they realized that byemploying such compositions, it becomes possible to improve the storagestability and stability in handling thereof simply and economically tothereby render vinyl ether group-containing (meth) acrylic esters suitedfor a wide range of industrial use. Hereinafter, these compositions aresometimes referred to as stabilized vinyl ether group-containing (meth)acrylic ester compositions.

It is considered that vinyl ether group-containing (meth) acrylic estersare polymerized when, during storage or handling, (1) radicals areformed as a result of abstraction of hydrogen atoms on carbon atomsadjacent to vinyl ether groups or (2) radicals are formed as a result offormation of ether peroxides from vinyl ether groups. In these cases, itis meant that vinyl ether group-containing (meth) acrylic estersinvolved in radical formation act as initiators. The above-mentionedcase (2) may be avoided by replacing the atmosphere with nitrogen and,on this occasion, esters are to be handled in an atmosphere containingmolecular oxygen to prevent polymerization of (meth) acryloyl groups dueto free of oxygen. On the other hand, with vinyl ethers other than(meth) acrylic esters or with vinyl ether group-free (meth) acrylicesters, such an event as mentioned above under (1) or (2) generally willnot occur. Thus, as compared with these, vinyl ether group-containing(meth) acrylic esters have insufficient stability. While those (meth)acrylic esters which have ether groups may exceptionally form radicalsas a result of abstraction of hydrogen atoms on carbon atoms adjacent toether groups, the rate of hydrogen atom abstraction in vinyl ethergroup-containing (meth) acrylic esters is much faster and, even whencompared with such (meth) acrylic esters, vinyl ether group-containing(meth) acrylic esters are insufficient in stability.

The present inventors paid their attention to these causes leading todecreased stability of vinyl ether group-containing (meth) acrylicesters and found that the problems mentioned above can be solvedsuccessfully by the above-mentioned contrivances that have so far neverbeen made. In an aspect, such finding has led to completion of thepresent invention.

The inventors further made investigations concerning how to handle vinylether group-containing (meth) acrylic esters and, as a result, found (1)that when the water concentration in the liquid phase containing vinylether group-containing (meth) acrylic esters is excessively high, vinylether groups tend to be decomposed or the ester moiety hydrolyzed and(meth) acrylic acids formed upon this hydrolysis may possibly causepolymerization of vinyl ether groups and (2) that when the oxygenconcentration in the gaseous phase in contact with vinyl ethergroup-containing (meth) acrylic esters is excessively low,(meth)acryloyl groups undergo polymerization due to free of oxygen and,when the oxygen concentration in the gaseous phase is excessively high,vinyl ether groups are deteriorated. They thus realized that byrestricting the water concentration in the liquid phase containing vinylether group-containing (meth) acrylic esters and/or the oxygenconcentration in the gaseous phase in contact with vinyl ethergroup-containing (meth) acrylic esters to a specific range, it becomespossible to handle vinyl ether group-containing (meth) acrylic esters ina stable manner.

Furthermore, they found (3) that vinyl ether group-containing (meth)acrylic esters easily, because of their easy polymerizability, undergoquality deterioration due to polymerization and/or decomposition whensubjected to irradiation with light, in particular visible rays and/orultraviolet rays and (4) that the quality deterioration due topolymerization or decomposition upon light irradiation is influenced bymolecular oxygen. They thus realized that by handling vinyl ethergroup-containing (meth) acrylic esters in lightproof structures, it isalso possible to handle the same in a stable condition and that byrestricting the molecular oxygen concentration in the gaseous phasewithin lightproof structures, it is possible to handle esters in a morestable condition.

They made further investigations concerning methods of producing vinylether group-containing (meth) acrylic esters and, as a result, foundthat when, in the method of producing vinyl ether group-containing(meth) acrylic esters by subjecting hydroxyl group-containing vinylethers and (meth) acrylic esters to transesterification reaction,hydroxyl group-containing vinyl ether compositions containing specificimpurities, not completely pure hydroxyl group-containing vinyl ethers,are used as raw materials, the desired esters can be produced in aneconomic manner and the byproduct lower alcohol can be removed moreeasily than in the case where pure hydroxyl group-containing vinylethers are used as raw materials and, thus, the time required for theproduction of vinyl ether group-containing (meth) acrylic esters can beshortened. In addition, they found that when, in carrying out thetransesterification reaction, the water content or oxygen concentrationin the reaction system is restricted to a specific range and/or thereaction is carried out in lightproof structures, vinyl ethergroup-containing (meth) acrylic esters can be produced stably in asimple and economical manner while inhibiting polymerization. The “timerequired for the production” so referred to herein means the time fromthe point of initiation of temperature raising in the reaction system tothe point when the yield of vinyl ether group-containing (meth) acrylicesters becomes constant as indicated by analysis of the reaction systemusing gas chromatography.

They also found that when, in purifying vinyl ether group-containing(meth) acrylic esters produced, the purification is carried out in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is within a specific range, or inlightproof structures, esters can be purified stably in a simple andeconomical manner while preventing the formation of impurities due topolymerization and decomposition during purification. Such findings haveled to completion of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A vinyl ether group-containing (meth) acrylic ester composition and amethod of producing the same according to the present invention aredescribed in the following.

The vinyl ether group-containing (meth) acrylic ester composition in thepresent invention comprises causing a radical 20 polymerizationinhibitor, or both of a radical polymerization inhibitor and a basiccompound, to coexist with a vinyl ether group-containing (meth) acrylicester represented by the following general formula (1):

CH₂═CR¹—COO—R²—O—CH═CH—R³  (1)

in the formula, R1 represents a hydrogen atom or a methyl group, R2represents an organic residue and R3 represents a hydrogen atom or anorganic residue.

The vinyl ether group-containing (meth) acrylic esters in the presentinvention are compounds represented by the general formula (1) andhaving specific structures containing a vinyl ether group represented by—O—CH═CH—R³ and a (meth) acryloyl group represented by CH₂═CR¹—COO—within one molecule. In the practice of the present invention, suchcompounds may be used singly or two or more of them may be used incombination.

In the practice of the present invention, the vinyl ethergroup-containing (meth) acrylic esters represented by the generalformula (1) may be those compounds in which the substituent representedby R¹ is a hydrogen atom or a methyl group, the substituent representedby R² is an organic residue and the substituent represented by R³ is ahydrogen atom or an organic residue.

In the present specification, the term “organic residues” as used hereinin defining compounds represented by the general formula means organicgroups bound to the fundamental structures constituting these compounds.

The organic residues represented by R² in the above general formula (1)are preferably, for example, straight, branched or cyclic alkylenegroups containing 2 to 20 carbon atoms, alkylene groups containing 2 to20 carbon atoms and having at least one oxygen atom in the form of anether linkage and/or an ester linkage within the structure thereof, andaromatic groups which contain 6 to 11 carbon atoms and may optionally besubstituted. Among them, alkylene groups containing 2 to 6 carbon atomsand alkylene groups containing 4 to 10 carbon atoms and having at leastone oxygen atom in the form of an ether linkage are preferred.

The organic residues represented by R³ in the above general formula (1)are preferably, for example, straight, branched or cyclic alkyl groupscontaining 1 to 10 carbon atoms and aromatic groups which contain 6 to11 carbon atoms and may optionally be substituted. Among them, alkylgroups containing 1 to 2 carbon atoms and aromatic groups containing 6to 8 carbon atoms are preferred.

As typical examples of vinyl ether group-containing (meth) acrylicesters represented by the above general formula (1), specifically, thefollowing ones are preferred:

2-Vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate,1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl(meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl(meth)acrylate, 6-vinyloxyhexyl (meth)acrylate,4-vinyloxymethylcyclohexylmethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl(meth)acrylate and 2-(vinyloxyethoxyethoxy)ethyl (meth)acrylate.

In the practice of the present invention, methods of producing vinylether group-containing (meth) acrylic esters represented by the generalformula (1) are preferably, for example, the method comprisingsubjecting a (meth) acrylic acid and a hydroxyl group-containing vinylether to esterification (method A), the method comprising subjecting a(meth) acrylic acid halide and a hydroxyl group-containing vinyl etherto esterification (method B), the method comprising subjecting a (meth)acrylic anhydride and a hydroxyl group-containing vinyl ether toesterification (method C), the method comprising subjecting a (meth)acrylic ester and a hydroxyl group-containing vinyl ether totransesterification (method D), the method comprising subjecting a(meth) acrylic acid and a halogen-containing vinyl ether toesterification (method E) and the method comprising subjecting a (meth)acrylic acid alkali (or alkaline earth) metal and a halogen-containingvinyl ether to esterification (method F). Among them, the methodcomprising subjecting a (meth) acrylic ester and a hydroxylgroup-containing vinyl ether to transesterification (method D) ispreferred. On that occasion, the method of producing a vinyl ethergroup-containing (meth) acrylic ester which is mentioned later herein ispreferably applied.

In accordance with the present invention, stabilized vinyl ethergroup-containing (meth) acrylic ester compositions can be obtained bycausing a radical polymerization inhibitor, or both of a radicalpolymerization inhibitor and a basic compound, to coexist with the abovevinyl ether group-containing (meth) acrylic esters. The radicalpolymerization inhibitor and basic compound may each be used singly or acombination of two or more species.

As methods of producing vinyl ether group-containing (meth) acrylicester compositions according to the present invention, (1) the methodcomprising adding a predetermined amount of a radical polymerizationinhibitor, or a predetermined amount of a radical polymerizationinhibitor and a predetermined amount of a basic compound, to the abovevinyl ether group-containing (meth) acrylic ester, (2) the methodcomprising adding the vinyl ether group-containing (meth) acrylic esterto a predetermined amount of a radical polymerization inhibitor, or apredetermined amount of a radical polymerization inhibitor and apredetermined amount of a basic compound, and (3) the method comprisinga combination of the above two methods are preferred. Such a productionmethod, namely the method of causing a radical polymerization inhibitor,or both of a radical polymerization inhibitor and a basic compound, tocoexist with the vinyl ether group-containing (meth) acrylic esterrepresented by the above general formula (1), also constitutes an aspectof the present invention.

The radical polymerization inhibitors to be used in accordance with theinvention may be those radical polymerization inhibitors in general use.Specifically, there may be preferably mentioned quinone typepolymerization inhibitors such as hydroquinone, methoxyhydroquinone,benzoquinone and p-tert-butylcatechol; alkylphenol type polymerizationinhibitors such as 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol,2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol and2,4,6-tri-tert-butylphenol; amine type polymerization inhibitors such asalkylated diphenylamine, N,N′-diphenyl-p-phenylenediamine,phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine,4-benzoyloxy-2,2,6,6-tetramethylpiperidine,1,4-dihydroxy-2,2,6,6-tetramethylpiperidine and1-hydroxy-4-benzoyloxy-2,2,2,6-tetramethylpiperidine; copperdithiocarbamate type polymerization inhibitors such as copperdimethyldithiocarbamate, copper diethyldithiocarbamate and copperdibutyldithiocarbamate; N-oxyl type polymerization inhibitors such as2,2,6,6-tetramethylpiperidine-N-oxyl,4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl,4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl and esters of4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl; etc. Among these,quinone type polymerization inhibitors, amine type polymerizationinhibitors, copper dithiocarbamate type polymerization inhibitors andN-oxyl type polymerization inhibitors are preferred radicalpolymerization inhibitors. Particularly preferred radical polymerizationinhibitors are hydroquinone, methoxyhydroquinone, benzoquinone,p-tert-butylcatechol, phenothiazine, alkylateddiphenylamine, copperdibutyldithiocarbamate, 2,2,6,6-tetramethylpiperidine-N-oxyl,4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, esters of4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and the like.

The level of addition of the above radical polymerization inhibitors mayvary according to the species of the vinyl ether group-containing (meth)acrylic ester represented by the general formula (1) but preferably isnot less than 0.00001% by weight, more preferably not less than 0.0001%by weight, still more preferably not less than 0.0002% by weigh,particularly preferably not less than 0.0005% by weight, but preferablynot more than 5% by weight, more preferably not more than 1% by weight,still more preferably not more than 0.5% by weight, particularlypreferably not more than 0.1% by weight, relative to said vinyl ethergroup-containing (meth) acrylic esters. The above range of the radicalpolymerization inhibitor addition level is preferred from the viewpointof polymerization inhibition and economy.

The basic compounds to be used in accordance with the present inventionare preferably, for example, alkali (alkaline earth) metal hydroxidessuch as lithium hydroxide, sodium hydroxide, potassium hydroxide, cesiumhydroxide, magnesium hydroxide and calcium hydroxide; alkali (alkalineearth) metal carbonate salts such as lithium hydrogen carbonate, sodiumhydrogen carbonate, potassium hydrogen carbonate, cesium hydrogencarbonate, magnesium hydrogen carbonate, calcium hydrogen carbonate,lithium carbonate, sodium carbonate, potassium carbonate, cesiumcarbonate, magnesium carbonate and calcium carbonate; alkali (alkalineearth) metal carboxylate salts such as lithium acetate, sodium acetate,potassium acetate, cesium acetate, magnesium acetate and calciumacetate; alkali (alkaline earth) metal alkoxides such as sodiummethoxide, sodium ethoxide, sodium butoxide, potassium methoxide,potassium ethoxide, potassium butoxide and calcium ethoxide; amines suchas ammonia, methylamine, ethylamine, butylamine, ethanolamine,dimethylamine, diethylamine, dibutylamine, diethanolamine,trimethylamine, triethylamine, tributylamine, tris (2-ethylhexyl) amine,triethanolamine, ethylenediamine, tetramethylethylenediamine, tren,1,4-diazabicyclo[2,2,2]octane, aniline, methylaniline, dimethylaniline,pyridine, piperidine, picoline, N,N-dimethyl-p-toluidine, lutidine,quinoline, isoquinoline and collidine; etc. Preferred among these basiccompounds are alkali (alkaline earth) metal hydroxides and amines.Particularly preferred basic compounds are sodium hydroxide, potassiumhydroxide, tris(2-ethylhexyl)amine, tributylamine and triethanolamine.

The level of addition of the above basic compounds may vary according tothe species of the vinyl ether group-containing (meth) acrylic esterrepresented by the general formula (1) but preferably is not less than0.00001% by weight, more preferably not less than 0.0001% by weight,still more preferably not less than 0.0002% by weigh, particularlypreferably not less than 0.0005% by weight, but preferably not more than5% by weight, more preferably not more than 1% by weight, still morepreferably not more than 0.5% by weight, particularly preferably notmore than 0.1% by weight, relative to said vinyl ether group-containing(meth) acrylic esters. The above range of the 35 basic compound additionlevel is preferred from the viewpoint of polymerization inhibition andeconomy.

By causing radical polymerization inhibitors, or both of radicalpolymerization inhibitors and basic compounds, to coexist with vinylether group-containing (meth) acrylic esters represented by the generalformula (1) in accordance with the present invention, it becomespossible to stabilize the above esters more effectively. The ratiobetween the radical polymerization inhibitor and basic compound on thatoccasion may be such that each are used at an addition level within theto range mentioned above.

The compositions of the present invention, namely “the vinyl ethergroup-containing (meth) acrylic esters and the radical polymerizationinhibitors”, or “the vinyl ether group-containing (meth) acrylic esterstogether with the radical polymerization inhibitors and the basiccompounds” may be used together with other components such as additives,organic solvents and the like.

In such cases, the ratio of the vinyl ether group-containing (meth)acrylic ester is preferably not less than 50% by weight, more preferablynot less than 70% by weight, still more preferably not less than 80% byweight, particularly preferably not less than 90% by weight, mostpreferably not less than 95% by weight, relative to the total amount ofthe composition.

The method of handling vinyl ether group-containing (meth) acrylicesters according to the present invention is now described.

The method of handling vinyl ether group-containing (meth) acrylicesters according to the invention is preferably (a) the mode in whichthe water concentration in a liquid phase containing the vinyl ethergroup-containing (meth) acrylic ester represented by the above generalformula (1) is at a level not higher than 15% by weight, (b) the mode inwhich the molecular oxygen concentration in the gaseous phase in contactwith the vinyl ether group-containing (meth) acrylic ester representedby the above general formula (1) is at a level of 0.01 to 15% by volume,(c) the mode in which the vinyl ether group-containing (meth) acrylicester represented by the above general formula 1) is handled in alightproof structure or (d) the mode in which the vinyl ethergroup-containing (meth) acrylic ester represented by the above generalformula (1) is handled in a lightproof structure while keeping themolecular oxygen concentration in the gaseous phase within saidlightproof structure at 0.01 to 22% by volume. It is also possible toappropriately combine the modes (a), (b), (c) and (d).

The term “handling” as used in the present invention means thetransportation of the vinyl ether group-containing (meth) acrylic estersin tank lorries or the like; the storage in tanks, containers or thelike; transfer through piping including pipes, valves, nozzles, etc.;and mixing and stirring in reaction vessels, reaction apparatuses,tanks, containers or the like. These operations may be conducted singlyor two or more of them may be conducted in appropriate combination.

In handling the vinyl ether group-containing (meth) acrylic esters ofthe general formula (1) according to the present invention, it ispreferred that radical polymerization inhibitors, or both of radicalpolymerization inhibitors and basic compounds be caused to coexist withthe esters. As the radical polymerization inhibitors and basiccompounds, there may respectively be used those specifically mentionedhereinabove.

The level of addition of the above radical polymerization inhibitors mayvary according to the species of the vinyl ether group-containing (meth)acrylic ester represented by the above general formula (1) butpreferably is not less than 0.0001% by weight, more preferably not lessthan 0.0005% by weight, still more preferably not less than 0.001% byweigh, particularly preferably not less than 0.002% by weight, butpreferably not more than 5% by weight, more preferably not more than 1%by weight, particularly preferably not more than 0.1% by weight,relative to said vinyl ether group-containing (meth) acrylic esters. Theabove range of the radical polymerization inhibitor addition level ispreferred from the viewpoint of yield, polymerization inhibition andeconomy.

The level of addition of the above basic compounds may vary according tothe species of the vinyl ether group-containing (meth) acrylic esterrepresented by the general formula (1) but preferably is not less than0.00001% by weight, more preferably not less than 0.0001% by weight,still more preferably not less than 0.0002% by weigh, particularlypreferably not less than 0.0005 by weight, but preferably not more than5% by weight, more preferably not more than 1% by weight, still morepreferably not more than 0.5% by weight, particularly preferably notmore than 0.1% by weight, relative to the vinyl ether group-containing(meth) acrylic esters. The above range of the basic compound additionlevel is preferred from the viewpoint of yield, polymerizationinhibition and economy.

In cases where the above radical polymerization inhibitors and basiccompounds are caused to coexist with the esters, the ratio between theradical polymerization inhibitor and basic compound may be such thateach are used at an addition level within the range mentioned above.

In handling vinyl ether group-containing (meth) acrylic esters in theabove-mentioned mode (a), the water concentration in the liquid phase,namely in the liquid phase containing vinyl ether group-containing(meth) acrylic esters represented by the above general formula (1), isadjusted within a specific range. The water concentration in the liquidphase is not more than 15% by weight, preferably not more than 5% byweight, more preferably not more than 3% by weight, still morepreferably not more than 1%, particularly preferably not more than 0.5%by weight. The above water concentration range is preferred from theviewpoint of stable handling.

For adjusting the water concentration in the above liquid phase to notmore than 15% by weight in the production of vinyl ethergroup-containing (meth) acrylic esters, the following methods arepreferred: the method comprising storing them promptly afterpurification by distillation or washing with water-insoluble solvents;the method comprising bubbling dried inert gas, such as nitrogen orargon and mixed gas composed of such inert gas and oxygen through theesters at room temperature or under warming conditions; the methodcomprising drying the esters with dehydrating agents such as molecularsieve, calcium chloride, magnesium sulfate, calcium sulfate or potassiumcarbonate, etc. These methods may appropriately be used in combination.

In handling vinyl ether group-containing (meth) acrylic esters in theabove-mentioned mode (b), the molecular oxygen concentration in thegaseous phase, namely in the gaseous phase in contact with the vinylether group-containing (meth) acrylic esters, is adjusted within aspecific range. The molecular oxygen concentration in the gaseous phaseis 0.01 to 15% by volume, preferably not lower than 0.02% by volume,more preferably not lower than 0.05% by volume, but preferably nothigher than 12% by volume, more preferably not higher than 10% byvolume. The above molecular oxygen concentration range is preferred fromthe viewpoint of stable handling and economy.

The “gaseous phase (gaseous phase in contact with the vinyl ethergroup-containing (meth) acrylic ester)” means the gaseous phase incontainers or structures, such as tank lorries or tanks, with the vinylether group-containing (meth) acrylic esters placed therein forhandling.

As for the method of adjusting the molecular oxygen concentration in theabove gaseous phase to 0.01 to 15% by volume, for example, the methodcomprising blowing inert gas, such as nitrogen or argon, into thegaseous phase and/or liquid phase and the method comprising blowingmixed gas composed of inert gas and oxygen into the gaseous phase and/orliquid phase are preferred.

Furthermore, in accordance with the present invention, 35 it ispreferred from the viewpoint of stable handling and economy that, inhandling the vinyl ether group-containing (meth) acrylic esters, themolecular oxygen concentration in the above gaseous phase be adjusted to0.01 to 15% by volume and the water concentration in the liquid phasecontaining the vinyl ether group-containing (meth) acrylic ester beadjusted to not higher than 15% by weight. In this case, the adjustmentmethods, the preferred molecular oxygen concentration range and thepreferred water concentration range are the same as mentioned above.

In handling vinyl ether group-containing (meth) acrylic esters in theabove-mentioned mode (c), handling them in lightproof structures makesstable handling possible.

The “lightproof structures” used in handling according to the presentinvention are structures made of lightproof materials, such asstructures for transportation for example tank lorries; structures forstorage for example tanks, drums, bottles and cans; structures fortransfer for example pipes, nozzles and valves; and structures formixing and stirring for example reaction vessels, tanks and containers;etc. The portion of the inside surface area of the structure to whichlight can reach is preferably not more than 20%, more preferably notmore than 15%, still more preferably not more than 10%, particularlypreferably not more than 8%, of the whole inside surface area of thestructure. The “lightproof materials” as so referred to herein arematerials substantially impermeable to light (visible rays, ultravioletrays and infrared rays). Furthermore, the structure inside surfaceportion to which light can reach or the structure inside surface portionto which light cannot reach may be continuous or discontinuous.

The lightproof materials mentioned above include, for example, aspreferred species, iron and steel such as industrial pure iron, carbonsteel (JISG-SS, JISG-SC, JISG-SB, JISG-SM, JISG-SGP, JISG-STGP,JISG-STS, JISG-STB, JISG-STL, JISG-STKIM, JISG-SWR, JISG-SK, JISG-SF,JISG-SC, etc.), cast iron (JISG-FC, JISG-FCD, JISG-FCM, etc.), low-alloysteel (JISG-SNC, JISG-SNCM, JISG-SCr, JISG-SCM, JISG-SACM, JISG-SCA,etc.), low-alloy cast iron (nitensil, nihard, acicular, etc.),low-nickel steel (JISG-STPL, JISG-STBL, JES-Ni, ASTM-A203, etc.), nickelsteel (ASTMA353, etc.), chrome stainless steel (JISG-SUH1, JISG-SUH2,JISG-SUH3, AISI-TP501, AISI-TP503, etc.), etc.; high silicon cast iron;high nickel cast iron such as 15% Ni cast iron (Ni-Resist1, etc.), 20%Ni cast iron (Ni-Resist2, etc.), 30% Ni cast iron (Ni-Resist3, etc.),etc.; high chromium steel such as high Cr cast iron (Nirosta, etc.),high Cr—Mo cast iron, etc.

Further includes martensitic stainless steel such as 13 Cr steel(SUS403, SUS410, SUS414, SUS416, etc.), 13 Cr high carbon steel (SUS420,etc.), 16 Cr 2 Ni steel (SUS431, SUS440A, SUS440B, SUS440C, etc.), etc.;ferritic stainless steel such as 18 Cr steel (SUS420, etc.), 25 Cr steel(SUS446, etc.), 13 Cr—Al steel (SUS405, etc.), etc.; austeniticstainless steel such as 18-8 steel (SUS301, SUS302, SUS303, SUS304,SUS305, SUS308, SUS321, SUS347, etc.), 18-8L steel (SUS304L, etc.),18-8Mo steel (SUS316, SUS317, etc.), 18-8MoL steel (SUS316L, etc.),22Cr-12Ni steel (SUS309, SUS309S, etc.), 25Cr-20Ni steel (SUS310,SUS310S, SUS314, etc.), etc.; special austenitic stainless steel such as20 alloys (Worthite, Durimet20, Carpenter20, Aloyco20, FA20, etc.), HNalloys (Chromax, etc.), etc.; Fe—Cr—Al alloys such as Fe—Cr—Al—Si alloys(Sicroma18, Sicroma19, Sicroma110, Sicroma111, Sicroma112, etc.),Fe—Cr—Al—Co alloys (KanthalA, etc.), etc.; high manganese steel such asJIS-SCMnH, etc.; copper and copper alloys such as industrial pure copper(JIS-CuP, JIS-CuB, JIS-CuT, JIS-DCuP, JIS-DCuT, etc.), Cu—Al alloys(JIS-ABP, JIS-ABB, JIS-BsTF, aluminum bronze, aluminum brass, etc.),Cu—Si alloys (JIS-SiBT, JIS-SzBC, siliconbronze, Everdur, ARalloys,Silzinbronze, etc.), Cu—Sn—Palloys (JIS-PBP, JIS-PBS, JIS-PBB, JIS-PBC,phosphor bronze, etc.), Cu—Sn—Zn alloys (JIS-BsC, bronze casting, etc.),Cu—Zn alloys (JIS-NBsP, etc.), Cu—Zn—Sn alloys (Red-Brass, etc.), Cu—Znalloys (JIS-BsP, JIS-LBC, JIS-RBsP, brass, leaded brass, red brass,etc.), etc.; Cu—Ni alloys such as Cu—Ni 20 (cupro-nickel, JIS-CNTF2,etc.), Ni-Aa (nickel silver, German silver, JIS-NSP, JIS-SNP1, etc.),Cu—Ni 30 (cupro-nickel, JIS-CNTF3, JIS-CNP3, etc.), etc.; aluminum andaluminum alloys such as industrial pure aluminum JIS-A1R, JIS-A1B,JIS-A1V, JIS-A1W, JIS-A1T, ALCOA-EC, ALCOA-1050, ALCOA-1060, ALCOA-1100,ALCOA-1130, ALCOA-1175, ALCOA-1260, etc.), highly pure aluminum, Al—Mnalloys (JIS-A2P3, J1S-A2T3, ALCOA-3003, etc.), high-tensile aluminumalloys (JIS-A3P, JIS-A3R, JIS-A3T, JIS-A3B, JIS-A3W, ALCOA-2014,ALCOA-2017, ALCOA-2024, ALCOA-2025, Duralumin, Super Duralumin, Yalloys, etc.), Al—Mg—Si alloys (JIS-A4F, ALCOA-6061, etc.), Al—Si alloys(JIS-AC3A, JIS-AC4ABC, ALCOA-4032, silumin casting, etc.), Al—Mg alloys(JIS-corrosion protected aluminum alloy Type 1, JIS-corrosion protectedaluminum alloy Type 2, JIS-corrosion protected aluminum alloy Type 7,ALCOA-5052, ALCOA-5056, ALCOA-5083, etc.), etc.; magnesium and magnesiumalloys such as industrial pure magnesium, magnesium alloys (JIS-MC,Dowmetal, Elektron, etc.), etc.; nickel such as industrial pure nickel(JIS-VNiP, JIS-VCNiP, JIS-VNiW, JIS-VCNiT, ASTM-B39, ASTM-160, ASTM-161,ASTM-162, etc.), etc.; Ni—Cr—Fe alloys such as 27A (Inconel, Colmonoy6,etc.), 27B (Inconel600, ASTM-B163, ASTM-B166, ASTM-B167, ASTM-B168,etc.), 27C, etc.; Ni—Cu alloys such as Monel (JIS-NCuT, JIS-NCuP,ASTM-B127, ASTM-B163, ASTM-B164, ASTM-B165, Monel 400, etc.), K Monel,etc.; Ni—Mo—Fe—Cr alloys such as 30A (HastelloyA, Contracid, etc.), 30B(ASTM-B333, ASTM-B335, ASTM-B494, HastelloyB, Chlorimet2, etc.), 30C(ASTM-B336, ASTM-B494, HastelloyC, Chlorimet3, etc.), 30D (HastelloyN,etc.), 30E (HastelloyF, etc.), 30F (Ni-o-nel, etc.), 30G (R-55, etc.),etc.; Ni—Cr—Cu—Mo alloys such as 31A (IlliumG, etc.), 31B (Illium98,etc.); Ni—Si alloys such as HastelloyD, etc.; cobalt alloys such asCo—Cr alloys (Stelite21, Stelite23, Stelite27, Stelite31, etc.),Co—Cr—Ni alloys (Haynes25, Haynes36, etc.), Co—Si alloys, etc.; lead andlead alloys such as industrial pure lead (JIS-PbP, JIS-PbT, JIS-PbTW,ASTM-B29, ASTM-B325, etc.), leadtelluride, hard lead (JIS-HPbP,JIS-HPbT, ASTM-B23, ASTM-B32, etc.), homogen lead fusion lining, etc.;tin; zinc and zinc alloys such as industrial pure zinc (JIS-zinc plate,ASTM-B6, etc.), zinc alloys (ASTM-B69, etc.), etc.; precious metals suchas silver, gold, platinum, niobium, tantalum (ASTM-B364, ASTM-B365,etc.) and platinum group and vanadium group metals; tungsten; titaniumand titanium alloys such as industrial pure titanium (JIS-TP, JIS-TTP,JIS-TB, JIS-TW, ASTM-B265, ASTM-B337, ASTM-B338, ASTM-B348, ASTM-B299,ASTM-B367, ASTM-B381, etc.), titanium alloys (ASTM-B265, ASTM-B348,ASTM-B367, ASTM-B381, etc.), etc.; zirconium and zirconium alloys suchas zirconium (ASTM-B349, ASTM-B350, ASTM-B351, ASTM-B352, ASTM-3353,ASTM-B356, etc.), zirconium alloys (Zircaloy-1, Zircaloy-2, Zircaloy-3,ASTM-B350, ASTM-B351, ASTM-B352, ASTM-B353, ASTM-B356, etc.), etc.;molybdenum such as ASTM-8384, ASTM-B385, ASTM-B386, ASTM-5387, etc.;chromium such as ASTM-B383, ASTM-B391, ASTM-B392, ASTM-B393, ASTM-B394,etc.; silicate products such as porcelain, earthenware, liparite,acid-resistant bricks, acid-resistant tiles, acid-resistant porcelain,silica cement, fire bricks, refractory mortar, vitreous enamel, etc.;concrete; sulfur cement; carbon and graphite products such as carbonformed products, graphite formed products, impervious carbon, imperviousgraphite, etc.; asbestos; synthetic resins such as opaque vinylidenechloride resin, opaque phenol resin, opaque furan resin, opaque vinylchloride resin, opaque ethylene tetrafluoride, opaque ethylenetrifluoride, opaque silicate resin, opaque polyethylene, opaquepolyisobutylene, opaque polystyrene, opaque epoxy resin, opaqueunsaturated polyester, opaque polyamide resin, opaque chlorinatedpolyether resin, opaque polycarbonate resin, opaque polyurethane resin,opaque urea resin, opaque melamine resin, etc.; asphalt; natural rubberand synthetic rubber such as opaque natural rubber, opaque naturalrubber hydrochloride or chlorinated natural rubber, opaque nitrilerubber, opaque styrene rubber, opaque butadiene-isobutylene syntheticrubber, opaque polychloroprene, opaque asbestos-filled rubber sheet,opaque butyl rubber, opaque polysulfide rubber, opaque chlorosulfonatedpolyethylene rubber, opaque fluorine rubber, opaque silicone rubber,opaque urethane rubber, etc.; glass such as glass of which inside and/oroutside is coated with opaque synthetic resin, glass of which insideand/or outside is coated with natural rubber or synthetic rubber, glassof which inside and/or outside is coated with metal, glass of whichinside and/or outside is plated with metal, etc.

Among these, iron and steel, high silicon cast iron, high nickel castiron, high chromium steel, martensitic stainless steel, ferriticstainless steel, austenitic stainless steel, special austeniticstainless steel, Fe—Cr—Al alloys, high manganese steel, copper andcopper alloys, Cu—Ni alloys, aluminum and aluminum alloys, magnesium andmagnesium alloys, nickel, Ni—Cr—Fe alloys, Ni—Cu alloys, Ni—Mo—Fe—Cralloys, Ni—Cr—Cu—Mo alloys, Ni—Si alloys, cobalt alloys, lead and leadalloys, tin, zinc and zinc alloys, tungsten, titanium and titaniumalloys, zirconium and zirconium alloys, molybdenum and chromium are morepreferred as the lightproof material. These lightproof materials can beused singly or two or more of them may be used in combination.

In handling a vinyl ether group-containing (meth) acrylic esterrepresented by the above general formula (1) in the above mode (d), theester is handled in a lightproof structure in an atmosphere such that amolecular oxygen concentration in the gaseous phase within the structureof 0.01 to 22% by volume, whereby quality degradation due topolymerization or decomposition can effectively be prevented and thevinyl ether group-containing (meth) acrylic ester can be handled in amore stable manner.

The molecular oxygen concentration in the gaseous phase within the abovestructures is preferably not lower than 0.02% by volume, particularlypreferably not lower than 0.05% by volume, but preferably not higherthan 18% by volume, particularly preferably not higher than 15% byvolume. If the molecular oxygen concentration in the gaseous phasewithin the structures is lower than 0.01% by volume, vinyl ethergroup-containing (meth) acrylic esters may undergo polymerization due tofree of oxygen. If the molecular oxygen concentration in the gaseousphase within the structures is higher than 22% by volume, qualitydegradation may occur due to polymerization or decomposition. Therefore,the above molecular oxygen concentration range is preferred from theviewpoint of quality, polymerization inhibition and economy.

It is necessary to handle the esters in lightproof structures since thequality degradation due to polymerization or decomposition mentionedabove is accelerated in optically transparent structures.

Available for use in adjusting the molecular oxygen concentration in thegaseous phase within the above structures to a specific range are (a)the method comprising feeding molecular oxygen or a gas containingmolecular oxygen, such as air, and an inert gas, such as nitrogen orargon, respectively to the structure and (b) the method comprisingadmixing molecular oxygen or a molecular oxygen-containing gas, such asair, with an inert gas, such as nitrogen or argon, in advance and thenfeeding the mixture to the structure, and the like. As for the gasfeeding method, the gases or gas mixture is fed to one or both of theliquid phase and gaseous phase either continuously or intermittently. Asfor the method of maintaining the molecular oxygen concentration in thegaseous phase in the structure within a specific range, the continuousor intermittent feeding method and the method comprising initialatmosphere substitution, followed by tight closure are preferred.

In handling vinyl ether group-containing (meth) acrylic estersrepresented by the above general formula (1), the handling temperatureis, specifically, preferably not lower than −20° C., more preferably notlower than −15° C., still more preferably not lower than −5° C.,particularly preferably not lower than 0° C. Conversely, it ispreferably not higher than 125° C., more preferably not higher than 100°C., still more preferably not higher than 80° C., particularlypreferably not higher than 60° C. The handling pressure may be atordinary pressure (atmospheric pressure), under pressure or underreduced pressure.

The method of producing a vinyl ether group-containing (meth) acrylicester according to the present invention is described in the following.

The method of producing a vinyl ether group-containing (meth acrylicester is a method of producing a vinyl ether group-containing (meth)acrylic ester represented by the above general formula (1). The abovemethod of producing a vinyl ether group-containing (meth) acrylic estercomprises reacting a hydroxyl group-containing vinyl ether representedby the following general formula (2):

R³—CH═CH—O—R²—OH  (2)

in the formula, R² represents an organic residue and R³ represents ahydrogen atom or an organic residue,

with a (meth) acrylic ester represented by the following general formula(3):

CH₂═CR¹—COOR⁴  (3)

in the formula, R¹ represents a hydrogen atom or a methyl group and R⁴represents an organic residue,

and in which the above hydroxyl group-containing vinyl ether contains atleast one compound selected from the group consisting of a divinyl etherrepresented by the following general formula (4):

R³—CH═CH—O—R²—O—CH═CH—R³  (4)

in the formula, R² represents an organic residue and the two R³ groupsare the same or different and each represents a hydrogen atom or anorganic residue,

a 2-substituted-1,3-dioxo compound represented by the following generalformula (5):

in the formula, R² represents an organic residue and represents ahydrogen atom or an organic residue,

and an unsaturated bond-containing vinyl ether 5 represented by thefollowing general formula (6):

R³—CH═CH—O—R⁵  (6)

in the formula, R³ represents a hydrogen atom or an organic residue; R⁵represents an organic residue containing an unsaturated bond representedby —CR⁶═CR⁷—; and R⁶ and R⁷ are the same or different and eachrepresents a hydrogen atom or an organic residue. In the presentspecification, such production method is referred to as the productionmethod (a).

In the above production method (a), vinyl ether group-containing (meth)acrylic esters can be produced economically by using hydroxylgroup-containing vinyl ether compositions containing at least onecompound selected from the group consisting of divinyl ethersrepresented by the above general formula (4), 2-substituted-1,3-dioxocompounds represented by the above general formula (5) and unsaturatedbond-containing vinyl ethers represented by the above general formula(6) as a raw material (raw material composition) without using anentirely pure hydroxyl group-containing vinyl ether as a raw materialand, by using such hydroxyl group-containing vinyl ether compositions,it becomes possible to remove the byproduct lower alcohols more easilyand curtail the time for producing the vinyl ether group-containing(meth) acrylic esters as compared with the case of using the entirelypure hydroxyl group-containing vinyl ethers.

In accordance with the present invention, the starting 30 materialalcohols in the transesterification reaction are compositions containinghydroxyl group-containing vinyl ethers. The above hydroxylgroup-containing vinyl ethers may be the compounds represented by theabove general formula (2), in which the substituent represented by R³ isa hydrogen atom or an organic residue and the substituent represented byR² is an organic residue.

The above R² and R³ are the same as the R² and R³ in the above generalformula (1), respectively.

Typical examples of the hydroxyl group-containing vinyl ethersrepresented by the above general formula (2) specifically to include thefollowing preferred ones:

-   -   2-Hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether,        4-hydroxybutyl vinyl ether, 4-hydroxycyclohexyl vinyl ether,        1,6-hexanediol monovinyl ether, 1,4-cyclohexanedimethanol        monovinyl ether, diethylene glycol monovinyl ether, triethylene        glycol monovinyl ether and dipropylene glycol monovinyl ether.

The raw material compositions used in the practice of the inventioncontain, in addition to the hydroxy-containing vinyl ethers representedby the above general formula (2), at least one compound selected fromthe group consisting of divinyl ethers represented by the above generalformula (4), 2-substituted-1,3-dioxo compounds represented by the abovegeneral formula (5) and unsaturated bond-containing vinyl ethersrepresented by the above general formula (6). The divinyl ethers of theabove general formula (4), 2-substituted-1,3-dioxo compound of the abovegeneral formula (5) and unsaturated bond-containing vinyl ethers of theabove general formula (6) may be contained respectively singly or two ormore of them may be contained.

The lower limit to the total amount of the impurities represented by theabove general formulas (4), (5) and (6) is preferably not less than0.01% by weight, more preferably not less than 0.05% by weight, stillmore preferably not less than 0.1% by weight, particularly preferablynot less than 0.5% by weight, but preferably not more than 70% byweight, more preferably not more than 50% by weight, still morepreferably not more than 30% by weight, particularly preferably not morethan 20% by weight, relative to the raw material composition. The aboveimpurity content range is preferred from the viewpoint of reaction rate,yield and economy.

The impurities represented by the above general formula 4), the abovegeneral formula (5) and the above general formula (6) are preferablycontained in the starting material hydroxyl group-containing vinylethers of the above general formula (2). They may also occur in thereaction system, however, as a result of intentional addition to thereaction system or formation during the reaction, for instance.

In cases where the above impurities occur in the reaction system, thelower limit to the total amount thereof is preferably not less than0.001% by weight, more preferably not less than 0.005% by weight,particularly preferably not less than 0.01% by weight, but preferablynot more than 10% by weight, more Preferably not more than 8% by weight,still more preferably not more than 5% by weight, particularlypreferably not more than 3% by weight, relative to the reaction system.The above impurity content range is preferred from the viewpoint ofreaction rate, yield and economy.

One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in the practice of the present inventionis the divinyl ethers. The divinyl ethers may be those compoundsrepresented by the above general formula (4), in which the substituentrepresented by R³ may be the same or different and each is a hydrogenatom or an organic residue and the substituent represented by R² is anorganic residue.

The above R² and R³ are the same as mentioned above.

Typical examples of the divinyl ethers represented by the above generalformula (4) specifically include such preferred ones as divinyl ether,ethylene glycol divinyl ether, propylene glycol divinyl ether,propanediol divinyl ether, butanediol divinyl ether, 1,4-cyclohexanedivinyl ether, 1,6-hexanediol divinyl ether, 1,4-cyclohexanedimethanoldivinyl ether, diethylene glycol divinyl ether, triethylene glycoldivinyl ether and dipropylene glycol divinyl ether.

One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in accordance with the present inventionis the 2-substituted-1,3-dioxo compounds, and may be the compoundsrepresented by the general formula (5), in which the substituentrepresented by R³ is a hydrogen atom or an organic residue and thesubstituent represented by R² is an organic residue.

The above R² and R³ are the same as mentioned above.

Typical examples of the 2-substituted-1,3-dioxo compounds represented bythe above general formula (5) specifically include such preferred onesas 2-methyl-1,3-dioxolane, 2,4-dimethy1-1,3-dioxolane,2-methyl-1,3-dioxane, 2-methyl-1,3-dioxepane, 1,6-hexanediolacetaldehyde cyclic acetal, diethylene glycol acetaldehyde cyclicacetal, triethylene glycol acetaldehyde cyclic acetal and dipropyleneglycol acetaldehyde cyclic acetal.

One species of the impurities to be contained in the hydroxylgroup-containing vinyl ethers in accordance with the present inventionis the unsaturated bond-containing vinyl ethers, and may be thecompounds represented by the above general formula (6), in which thesubstituent represented by R³ is a hydrogen atom or an organic residueand the substituent represented by R⁵ is an organic residue containingan unsaturated bond represented by —CR⁶═CR⁷—.

The above R³ is the same as mentioned above.

The organic residue represented by R⁵ in the above general formula (6)and containing an unsaturated bond represented by —CR⁶═CR⁷—, in which R⁶and R⁷ are the same or different and each is a hydrogen atom or anorganic residue, is an organic residue having a structure derived fromthe —R²—OH group in the general formula (2) by dehydration.Specifically, when —R²—OH is —CH₂CH₂CH₂—OH, for instance, the organicresidue represented by R⁵ is —CH₂CH═CH₂ and both of R⁶ and R⁷ arehydrogen atoms. When —R²—OH is —CH₂CH(OH)CH₃, the organic residuerepresented by R⁵ is —CH₂CH═CH₂ or —CH═CH—CH₃ and R⁶ is a hydrogen atomin either case and R⁷ is a hydrogen atom or a methyl group.

Typical examples of the unsaturated bond-containing vinyl ethersrepresented by the above general formula (6) specifically include suchpreferred ones as 2-propenyl vinyl ether, 1-propenyl vinyl ether,3-butenyl vinyl ether and 5-hexenyl vinyl ether.

The (meth) acrylic esters, which are starting materials in the practiceof the invention may be those compounds represented by the above generalformula (3), in which the substituent represented by R¹ is a hydrogenatom or a methyl group and the substituent represented by R⁴ is anorganic residue.

The organic residues represented by R⁴ in the above general formula (3)are preferably, for example, straight, branched or cyclic alkyl groupscontaining 1 to 8 carbon atoms and aromatic groups containing 6 to 10carbon atoms, which may optionally be substituted. Among these, alkylgroups containing 1 to 4 carbon atoms are preferably used.

Typical examples of the (meth) acrylic esters represented by the abovegeneral formula (3) are, specifically, as preferred ones, lower alkyl(meth) acrylic esters such as methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl(meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate andtert-butyl (meth)acrylate. These may be used singly or in admixture.

In the practice of the invention, the transesterification reactions arepreferably carried out in the presence of transesterification catalysts.The alcohols formed as reaction byproducts are preferably removed fromthe reaction system.

As for the reaction mole ratio between the (meth) acrylic esters and thehydroxyl group-containing vinyl ethers in the above transesterificationreactions, specifically, the (meth) acrylic esters/hydroxylgroup-containing vinyl ethers mole ratio is preferably within the rangeof 6/1 to 1/5 , more preferably within the range of 5/1 to 1/3, stillmore preferably within the range of 4/1 to 1/2, particularly preferablywithin the range of 3/1 to 1/1. The above mole ratio range is preferredfrom the viewpoint of yield and economy.

The above transesterification catalysts are, specifically, as preferredones, oxides such as calcium oxide, barium oxide, lead oxide, zinc oxideand zirconium oxide; hydroxides such as potassium hydroxide, sodiumhydroxide, lithium hydroxide, calcium hydroxide, thallium hydroxide, tinhydroxide, lead hydroxide and nickel hydroxide; halides such as lithiumchloride, calcium chloride, tin chloride, lead chloride, zirconiumchloride and nickel chloride; carbonate salts such as potassiumcarbonate, rubidium carbonate, cesium carbonate, lead carbonate, zinccarbonate and nickel carbonate; hydrogen carbonate salts such aspotassium hydrogen carbonate, rubidium hydrogen carbonate and cesiumhydrogen carbonate; phosphate salts such as sodium phosphate, potassiumphosphate, rubidium phosphate, lead phosphate, zinc phosphate and nickelphosphate; nitrate salts such as lithiumnitrate, calciumnitrate, leadnitrate, zinc nitrate and nickel nitrate; carboxylate salts such aslithium acetate, calcium acetate, lead acetate, zinc acetate and nickelacetate; alkoxy compounds such as sodium methoxide, sodium ethoxide,potassium methoxide, potassium ethoxide, potassium tert-butoxide,calcium methoxide, calcium ethoxide, barium methoxide, barium ethoxide,tetraethoxytitanium, tetrabutoxytitanium andtetra(2-ethylhexanoxy)titanium; acetylacetonato complexessuchaslithiumacetylacetonate, zirconiaacetylacetonate, zincacetylacetonate, dibutoxytin acetylacetonate and dibutoxytitaniumacetylacetonate; quaternary ammonium alkoxides such astetramethylammonium methoxide, tetramethylammonium tert-butoxide andtrimethylbenzylammonium ethoxide; dialkyltin compounds such asdimethyltin oxide, methylbutyltin oxide, dibutyltin oxide and dioctyltinoxide; distannoxanes such as bis(dibutyltin acetate) oxide andbis(dibutyltin laurate) oxide; and dialkyltin dicarboxylate salts suchas dibutyltin diacetate and dibutyltin dilaurate. These may be usedsingly or two or more of them may be used in combination.

Among these transesterification catalysts, potassium carbonate, cesiumcarbonate, tetraethoxytitanium, tetrabutoxytitanium,tetra(2-ethylhexanoxy)titanium, zirconia acetylacetonate, dibutyltinoxide, dioctyltin oxide, bis(dibutyltin acetate) oxide, bis(dibutyltinlaurate) oxide, dibutyltin diacetate and dibutyltin dilaurate arepreferably used.

The level of addition of the above transesterification catalysts is,specifically, preferably not less than 0.001 mole percent, morepreferably not less than 0.005 mole percent, still more preferably notless than 0.01 mole percent, particularly preferably not less than 0.05mole percent, but preferably not more than 20 mole percent, morepreferably not more than 15 mole percent, still more preferably not morethan 10 mole percent, particularly preferably not more than 5 molepercent. The above range of transesterification catalyst addition levelis preferred from the viewpoint of yield and economy.

As the method of removing the above byproduct alcohols, for example, themethod comprising carrying out the reaction under reduced pressure, themethod comprising carrying out the reaction using azeotropic solventsand the method comprising carrying out the reaction in the presence ofadsorbents are preferred. Among these, the method comprising carryingout the reaction under reduced pressure and the method comprisingcarrying out the reaction using azeotropic solvents are preferred.

The above azeotropic solvents may be ones which do not adversely affectthe reaction. Specifically, ethers such as diethyl ether, diisopropylether and dibutyl ether; aromatic hydrocarbons such as benzene, tolueneand xylene; aliphatic hydrocarbons such as pentane, hexane, heptane andcyclohexane; halogenated hydrocarbons such as chloroform, methylenechloride, 1,2-dichloroethane and chlorobenzene; and the like arepreferred. These azeotropic solvents may be used singly or two or moreof them may be used in combination.

The level of addition of the above azeotropic solvents is, specifically,preferably not less than 0% by weight relative to the total weight ofthe (meth) acrylic esters represented by the general formula (3) and thehydroxyl group-containing vinyl ethers represented by the generalformula (2). Conversely, it is preferably not more than 300% by weight,more preferably not more than 200% by weight, still more preferably notmore than 150% by weight, particularly preferably not more than 100% byweight, relative to the total weight of the (meth) acrylic estersrepresented by the general formula (3) and the hydroxyl group-containingvinyl ethers represented by the general formula (2). The above range ofthe organic solvent addition level is preferred from the viewpoint ofyield and economy.

The (meth) acrylic ester used in excess as well as the impuritiesrepresented by the above general formulas (4), (5) and (6) may alsoserve as the azeotropic solvent.

The reaction temperature for the above reaction is preferably not lowerthan the boiling point or azeotropic point of the byproduct alcohol.Specifically, the temperature is preferably not lower than 40° C., morepreferably not lower than 50° C., particularly preferably not lower than60° C. Conversely, it is preferably not higher than 180° C., morepreferably not higher than 170° C., particularly preferably not higherthan 160° C. The reaction pressure may be at ordinary pressure, underpressure or under reduced pressure. The reaction time can appropriatelybe selected so that the above reaction can be driven to completion.

From the viewpoint of polymerization inhibition and yield, theproduction of the vinyl ether group-containing (meth) acrylic esters ofthe above general formula (1) is preferably carried out in the presenceof polymerization inhibitors. As for the polymerization inhibitors,those radical polymerization inhibitors mentioned above are preferablyused, for instance, and one or two or more of them may be used.

The level of addition of the above polymerization inhibitors may varyaccording to the species of the (meth) acrylic ester of the generalformula (3) as used and the species of the product vinyl ethergroup-containing (meth) acrylic ester of the general formula (1) but ispreferably within the range of not less than 0.0001% by weight, morepreferably not less than 0.0002% by weight, still more preferably notless than 0.0005% by weight, particularly preferably not less than0.001% by weight, but preferably not more than 5% by weight, morepreferably not more than 1% by weight, still more preferably not morethan 0.5% by weight, particularly preferably not more than 0.1% byweight relative to the (meth) acrylic esters of the general formula (3).The above range of polymerization inhibitor addition level is preferredfrom the viewpoint of yield, polymerization inhibition and economy.

In the production method according to the invention, it is alsopreferable to cause basic compounds to coexist with radicalpolymerization inhibitors. Suited for use as basic compounds are thesame ones as mentioned hereinabove, and one or two or more of them maybe used.

The level of addition of the above basic compounds may vary according tothe species of the starting material hydroxyl group-containing vinylether and the species of the product vinyl ether group-containing (meth)acrylic ester of the general formula (1) but preferably is not less than0.0001% by weight, more preferably not less than 0.0002% by weight,still more preferably not less than 0.0005% by weight, particularlypreferably not less than 0.001% by weight, but preferably not more than5% by weight, more preferably not more than 1% by weight, still morepreferably not more than 0.5% by weight, particularly preferably notmore than 0.1% by weight, relative to the above hydroxylgroup-containing vinyl ethers. The above range of basic compound ispreferred from the viewpoint of yield, polymerization inhibition andeconomy.

As the method of producing vinyl ether group-containing (meth; acrylicesters according to the present invention, the method of producing avinyl ether group-containing (meth) acrylic ester which comprisesreacting a hydroxyl group-containing vinyl ether represented by theabove general formula (2) with a (meth) acrylic ester represented by theabove general formula (3) in The presence of not more than 5% by weightof water (production method (b)), the method of producing a vinyl ethergroup-containing (meth) acrylic ester which comprises reacting ahydroxyl group-containing vinyl ether represented by the above generalformula (2) with a (meth) acrylic ester represented by the above generalformula (3) in an atmosphere such that a molecular oxygen concentrationis 0.01 to 10% by volume (production method (c)), the method ofproducing a vinyl ether group-containing (meth) acrylic ester which iscarried out in a lightproof structure (production method (d)) and themethod of producing a vinyl ether group-containing (meth) acrylic esterwhich is carried out in a lightproof structure in an atmosphere suchthat a molecular oxygen concentration in the gaseous phase within saidlightproof structure is 0.01 to 15% by volume (production method (e))are preferred.

Also suited are the method of producing a vinyl ether group-containing(meth) acrylic ester which comprises reacting a hydroxylgroup-containing vinyl ether represented by the above general formula(2) with a (meth) acrylic ester represented by the general formula (3)in the presence of an N-nitrosophenylhydroxylamine salt represented bythe following general formula (7):

in the formula, M represents a metal atom or an ammonium group and nrepresents an integer equal to the valence of M (production method (f))and the method of producing a vinyl ether group-containing (meth)acrylic ester which comprises reacting a hydroxyl group-containing vinylether represented by the above general formula (2) with a (meth) acrylicester represented by the above general formula (3) in an atmosphere suchthat a molecular nitrogen monoxide (NO) and/or molecular nitrogendioxide (NO₂) concentration in the gaseous phase in the reaction systemis 0.01 to 10% by volume (production method (g)). One of theseproduction methods may be carried out or the production methodsmentioned above may be carried out in appropriate combination. It ispreferred, however, that they be carried out in appropriate combination.

In the above production methods (b), (c), (f) and (g), hydroxylgroup-containing vinyl ethers of the above general formula (2) and(meth) acrylic esters of the above general formula (3) are subjected totransesterification reaction. The hydroxyl group-containing vinyl ethersof the above general formula (2), the (meth) acrylic esters of the abovegeneral formula (3), the methods of subjecting these totransesterification reaction and the reactions conditions, and the like,are the same as those mentioned hereinabove. Further, in carrying outthe transesterification reaction, the reaction is preferably carried outin the presence of the above-mentioned radical polymerization inhibitorsor the radical polymerization inhibitors and the basic compounds. Thelevels of addition of the radical polymerization inhibitors and basiccompounds are the same as in the production method (a).

The above production method (b) is carried out in the presence of notmore than 5% by weight of water. Thus, the amount of water in the liquidphase in the reaction system is kept at not more than 5% by weightrelative to the total weight of the Liquid phase in the reaction system.In the above production method b), the amount of water in the reactionsystem, namely in the, Liquid phase in the reaction system, is not morethan 5% by weight, preferably not more than 3% by weight, morepreferably not more than 1% by weight, relative to the total weight ofthe liquid phase in the reaction system. The above water content rangeis preferred from the viewpoint of selectivity, yield and economy.

In the above production method (c), the transesterification reaction iscarried out in an atmosphere such that the molecular oxygenconcentration in the gaseous phase in the reaction system is 0.01 to 10%by volume. By selecting the molecular oxygen concentration in thegaseous phase in the reaction system in the above range, thepolymerization in the above reaction system can be effectively inhibitedand the desired vinyl ether group-containing (meth) acrylic ester can beproduced in high yields. In a preferred embodiment, the molecular oxygenconcentration in the gaseous phase in the above reaction system is notless than 0.02% by volume, more preferably not less than 0.05% byvolume, but preferably not more than 9% by volume, more preferably notmore than 8% by volume. The above molecular oxygen concentration rangeis preferred from the viewpoint of yield, polymerization inhibition inreaction system, explosion avoidance and economy.

Available for adjusting the molecular oxygen concentration in the abovegaseous phase to 0.01 to 10% by volume are (a: the method comprisingfeeding molecular oxygen or a molecular oxygen-containing gas, such asair, into a reaction vessel (vapors occurring therein) during reactionuntil that concentration falls within the range of 0.01 to 10% by volumerelative to the volume of the gaseous phase in the reaction system, (b)the method comprising feeding molecular oxygen or a molecularoxygen-containing gas, such as air, and an inert Gas, such as nitrogenor argon, respectively into a reaction vessel (vapors occurring therein)during reaction until the concentration falls within the range of 0.01to 10% by volume relative to the volume of the gaseous phase in thereaction system, (c) the method comprising admixing molecular oxygen ora molecular oxygen-containing gas, such as air, with an inert gas, suchas nitrogen or argon, in advance and feeding the mixture into a reactionvessel (vapors occurring therein) during reaction until theconcentration falls within the range of 0.01 to 10% by volume relativeto the volume of the gaseous phase in the reaction system, and the like.

As the methods for feeding molecular oxygen or a mixed gas containingmolecular oxygen to the reaction system, it may be fed to one or both ofthe liquid phase and gaseous phase in the reaction system eithercontinuously or intermittently.

In the above production method (f), the polymerization in the abovereaction system can be effectively inhibited and the desired vinyl ethergroup-containing (meth) acrylic esters can be produced in high yield bycausing N-nitrosophenylhydroxylamine salts represented by the abovegeneral formula (7) to coexist in the step of the transesterificationreaction. The N-nitrosophenylhydroxylamine salts of the general formula(7) may be used singly or two or more species may be used incombination.

Referring to the above general formula (7), typical examples of themetal atom represented by M are aluminum, copper, iron(III), tin, zinc,magnesium and the like. Among these, aluminum is particularly preferred.

The level of addition of the above N-nitrosophenylhydroxylamine salts ispreferably not less than 0.00001% by weight, more preferably not lessthan 0.0001% by weight, still more preferably not less than 0.0002% byweight, particularly preferably not less than 0.0005% by weight, butpreferably not more than 5% by weight, more preferably not more than %by weight, still more preferably not more than 0.5% by weight,particularly preferably not more than 0.1% by weight, relative to the(meth) acrylic esters represented by the above general formula (3). Theabove range of N-nitrosophenylhydroxylamine salt addition level ispreferred from the viewpoint of yield, polymerization inhibition inreaction system, and economy.

In the above production method (g), the polymerization in the abovereaction system can be effectively inhibited and the desired vinyl ethergroup-containing (meth) acrylic esters can be produced in high yields bycarrying out the transesterification reaction in an atmosphere such thatthe molecular nitrogen monoxide (NO) and/or molecular nitrogen dioxide(NO₂) concentration in the gaseous phase in the reaction system is 0.01to 10% by volume.

The molecular nitrogen monoxide (NO) and/or molecular nitrogen dioxide(NO₂) concentration in the gaseous phase in the above reaction system ispreferably not less than 0.01% by volume, more preferably not less than0.02% by volume, still more preferably not less than 0.05% by volume,but preferably not more than 10% by volume, more preferably not morethan 9% by volume, still more preferably not more than 8% by volume. Theabove range of molecular nitrogen monoxide (NO) and/or molecularnitrogen dioxide (NO₂) concentration is preferred from the viewpoint ofyield, polymerization inhibition in reaction system, explosionavoidance, and economy.

For adjusting the molecular nitrogen monoxide (NO) and/or molecularnitrogen dioxide (NO₂) concentration on the above gaseous phase to 0.01to 10% by volume, there are available, (a) the method comprising feedinga gas containing molecular nitrogen monoxide (NO) and/or molecularnitrogen dioxide (NO₂) into a reaction vessel (vapors occurring therein)during reaction until The concentration falls within 0.01 to 10.% byvolume relative to the volume of the gaseous phase in the reactionsystem, (b) the method comprising feeding molecular nitrogen monoxide(NO) and/or molecular nitrogen dioxide (NO₂) and an inert gas, such asnitrogen or argon, respectively into a reaction vessel (vapors occurringtherein) during reaction until the concentration falls within 0.01 to10% by volume relative to the volume of the gaseous phase in thereaction system, and (c) the method comprising admixing molecularnitrogen monoxide (NO) and/or molecular nitrogen dioxide (NO2) with aninert gas, such as nitrogen or argon, in advance and feeding the mixtureinto a reaction vessel (vapors occurring therein) during reaction untilthe concentration falls within 0.01 to 10% by volume relative to thevolume of the gaseous phase in the reaction system.

As the method for feeding molecular nitrogen monoxide (NO) and/ormolecular nitrogen dioxide (NO₂), or a mixed gas containing molecularnitrogen monoxide (NO) and/or molecular nitrogen dioxide (NO₂) to thereaction system, it may be fed to one or both of the liquid phase andgaseous phase in the reaction system either continuously orintermittently.

The term “production” as used herein referring to the above productionmethods (d) and (e) includes, within the meaning thereof, the steps ofraw materials charging, reaction, reaction solution transfer and soforth. These steps may be carried out independently or two or more ofthem may be carried in appropriate combination. Among these, the rawmaterials charging step and the reaction step, in particular, are meantby the term.

The above production methods (d) and (e) can be applied, for example, incarrying out the above-mentioned production methods A to F. Among these,the production method which comprises subjecting (meth) acrylic estersand hydroxyl group-containing vinyl ethers to transesterificationreaction (production method D) is preferred from the industrialviewpoint. As the hydroxyl group-containing vinyl ethers and (meth)acrylic esters, the same ones as those hydroxyl group-containing vinylethers represented by the general formula (2) and those (meth) acrylicesters represented by the general formula (3), and the like arepreferred. The method of subjecting these to transesterificationreaction and the reaction conditions may be the same as mentionedreferring to the production methods mentioned above, for instance.

In cases where the mode of the above production methods (d) and (e) areapplied to the production methods A to F, it is preferred in each casethat radical polymerization inhibitors and/or basic compounds be causedto coexist. Furthermore, in carrying out the transesterificationreaction, the reaction is preferably carried out in the presence of theabove-mentioned radical polymerization inhibitors or the radicalpolymerization inhibitors and the basic compounds.

The level of addition of the radical polymerization inhibitors may varyaccording to the species of the starting material (meth) acryliccompound, such as (meth) acrylic acid, (meth) acrylic halide, (meth)acrylic anhydride, (meth) acrylic ester, (meth) acrylic acid alkali (oralkaline earth) metal salt or the like, and the level of addition of theabove basic compounds may vary according to the species of the startingmaterial vinyl ether, such as hydroxyl group-containing vinyl ether,halogen-containing vinyl ether or the like. However, they are the sameas in the production method (a).

According to the above production method (d), vinyl ethergroup-containing (meth) acrylic esters represented by the above generalformula (1) can be produced in a stable manner by producing them inlightproof structures. As the lightproof structures used in production,there may be mentioned structures made of lightproof materials such asreaction vessels, reaction apparatus, mixing apparatus, tanks, pipes,nozzles, valves and the like for the production purpose. The insidesurface area of the structures to which light can reach is the same asmentioned above. The lightproof materials are also preferably the sameones as mentioned above. According to the above production method (e),vinyl ether group-containing (meth) acrylic esters represented by theabove general formula (1) can be produced in a more stable manner byproducing them in lightproof structures on an atmosphere such that themolecular oxygen concentration on the gaseous phase within saidlightproof structures is 0.01 to 15% by volume.

In this manner, by carrying out the reaction while adjusting themolecular oxygen concentration in the gaseous phase within thelightproof structures to 0.01 to 15% by volume, it becomes possible toeffectively inhibit the polymerization of vinyl ether group-containing(meth) acrylic esters in the liquid phase and/or gaseous phase as wellas the formation of impurities and of peroxides, hence it becomespossible to produce the desired vinyl ether group-containing (meth)acrylic esters in high yields.

The molecular oxygen concentration in the gaseous phase within the abovelightproof structures is generally 0.01 to 15% by volume. Preferably,however, it is not less than 0.02% by volume, particularly preferablynot less than 0.05% by volume, but preferably not more than 12% byvolume, particularly preferably not more than 10% by volume. If themolecular oxygen concentration within the gaseous phase in thelightproof structures is less than 0.01% by volume, the startingmaterial (meth) acrylic compounds and the vinyl ether group-containing(meth) acrylic esters may undergo polymerization due to free of oxygen.If the molecular oxygen concentration in the gaseous phase within thestructures is higher than 15% by volume, the formation of impurities andof peroxides and the polymerization of the vinyl ether group-containing(meth) acrylic esters may occur. Therefore, the above molecular oxygenconcentration range is preferred from the viewpoint of yield,polymerization inhibition, and economy.

The above-mentioned formation of impurities and of peroxides andpolymerization of vinyl ether group-containing (meth) acrylic esters aremore accelerated in structures permeable to light and, therefore, it isnecessary to carryout 35 the production inside lightproof structures.

In adjusting the molecular oxygen concentration in the gaseous phasewithin the lightproof structures to 0.01 to 15% by volume, those methodsof adjusting the molecular oxygen concentration mentioned hereinabovecan be applied. As for the gas feeding method, the gas may be fed to oneor both of the liquid phase and gaseous phase either continuously orintermittently in each step of the production process.

The vinyl ether group-containing (meth) acrylic esters of the generalformula (1) produced by the above production methods can be obtained bypurifying the reaction solution.

As methods of purifying the vinyl ether group-containing (meth) acrylicesters represented by the above general formula (1), there maypreferably be applied, for example, the method of purifying a vinylether group-containing (meth) acrylic ester which is carried out in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 10% by volume (purificationmethod (a)), the method of purifying vinyl ether group-containing (meth)acrylic esters which is carried out in a lightproof structure in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 15% by volume (purificationmethod (b)) and a combination of these. The above-mentioned purificationmethod (a) and purification method (b) constitute a further aspect ofthe present invention.

The methods of purifying vinyl ether group-containing (meth) acrylicesters according to the invention are described below.

The above term “purification” used herein means procedures after whichthe vinyl ether group-containing (meth) acrylic esters represented bythe general formula (1) have improved concentration and/or purity ascompared with the value before that procedure. More specifically,procedures include raw materials recovery, catalysts recovery,neutralization, filtration, decantation, extraction, water washing,evaporation, distillation, column chromatography and other procedures.The above procedures may be performed singly or two or more may beperformed in appropriate combination. Among them, the distillationprocedure is particularly preferred.

As the “lightproof structures” used in the above purification, there maybe mentioned structures made of lightproof materials such asdistillation vessels, distillation towers, rectification towers,distillation apparatus, separation apparatus, filtration apparatus,mixing apparatus, tanks, pipes, nozzles, valves and the like, for thepurification purpose. The inside surface area of the structures to whichlight can reach is the same as mentioned above. The lightproof materialsare also preferably the same ones as mentioned above.

In the above purification method (a), the impurity formation due topolymerization and decomposition in the above process of purificationcan be effectively prevented and the desired vinyl ethergroup-containing (meth) acrylic esters can be purified stably in simpleand economical manners by carrying out the purification procedure in anatmosphere such that the molecular oxygen concentration in the gaseousphase in the purification system is 0.01 to 10% by volume.

The molecular oxygen concentration in the gaseous phase in the abovepurification system is 0.01 to 10% by volume. Preferably, however, it isnot less than 0.02% by volume, particularly preferably not less than0.05% by volume, but preferably not more than 9% by volume, particularlypreferably not more than 8% by volume. The above molecular oxygenconcentration range is preferred from the viewpoint of yield,polymerization inhibition, impurity formation prevention and economy.

In adjusting the molecular oxygen concentration to 0.01 to 10% byvolume, the above-mentioned methods of adjusting the molecular oxygenconcentration can be applied. As for the methods of gas feeding to thepurification system, the gas may be fed to one or both of the liquidphase and gaseous phase in the purification system either continuouslyor intermittently.

In the above purification method (b), the impurity formation due topolymerization and decomposition in the above process of purificationcan be effectively prevented and the desired vinyl ethergroup-containing (meth) acrylic esters can be purified stably in simpleand economical manners by carrying out the purification procedure inlightproof structures in an atmosphere such that the molecular oxygenconcentration in the gaseous phase in the purification system is 0.01 to15% by volume.

The molecular oxygen concentration in the gaseous phase in the abovepurification system is 0.01 to 15% by volume. Preferably, however, it isnot less than 0.02% by volume, particularly preferably not less than0.05% by volume, but preferably not more than 12% by volume,particularly preferably not more than 10% by volume. The above molecularoxygen concentration range is preferred from the viewpoint of yield,polymerization inhibition, and economy.

In adjusting the molecular oxygen concentration in the gaseous phase inthe above purification system to 0.01 to 15% by volume and in gasfeeding, the same methods as in the purification method (a) can beapplied.

As the use of the vinyl ether group-containing (meth) acrylic estercompositions according to the invention and of the vinyl ethergroup-containing (meth) acrylic esters produced and purified accordingto the invention, they can be used in a wide range, for example as rawmaterials in the medicinal and agricultural chemicals, as syntheticintermediates and further as polymerizable materials.

The present invention, which has the constitution mentioned above, canimprove the stability of vinyl ether group-containing (meth) acrylicesters by preventing the polymerization of the vinyl ethergroup-containing (meth) acrylic esters during storage and handlingthereof without impairing the polymerizability thereof and thus makes itpossible to handle the vinyl ether group-containing (meth) acrylicesters in a stable manner. It further makes it possible to produce andpurify vinyl ether group-containing (meth) acrylic esters in a simple,economical and stable manner while preventing the formation ofimpurities due to polymerization and decomposition in the process ofproduction or purification of the vinyl ether group-containing (meth)acrylic esters.

EXAMPLES

The following examples illustrate the present invention 10 in furtherdetail. They are, however, by no means limitative of the scope of theinvention.

Example 1

A vinyl ether group-containing (meth) acrylic ester composition wasprepared by adding 10 mg of methoxyhydroquinone, a radicalpolymerization inhibitor, to 100 g of 2-vinyloxyethyl acrylate. Thecomposition was placed in a sealed container and stored at 50° C. for120 days. Thereafter, as results of analyses by visual observation andby an HLC-8120 GPC type gel permeation chromatography (product of Tosoh;hereinafter referred to as “GPC”) with tetrahydrofuran as the carrier,neither discoloration nor high-molecular compound formation wasobserved.

Examples 2 to 12

The same procedure as in Example 1 was followed except that the vinylether group-containing (meth) acrylic ester and/or radicalpolymerization inhibitor used differed in species and/or the amountsthereof were varied. The species used, the amounts thereof and theresults of visual observation and GPC are shown in Table 1.

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 11 12 Vinyl ether group-containingVEA VEA VEM VEM VEEA VEEA VEEM VEEM VBA VBA VBM VBM (meth) acrylic ester(g) 100 100 100 100 100 100 100 100 100 100 100 100 Radicalpolymerization inhibitor MEHQ PTZ HQ TEMPO MEHQ TEMPO MEHQ TEMPO PTZTEMPO MEHQ PTZ (mg)  10  10  10  10  10  10  10  10  10  10  10  10Storage temperature 50° C. 50° C. 50° C. 50° C. 50° C. 50° C. 50° C. 50°C. 50° C. 50° C. 50° C. 50° C. Number of days of storage 120 120 120 120120 120 120 120 120 120 120 120 days days days days days days days daysdays days days days Visual observation No No No No No No No No No No NoNo change change change change change change change change change changechange change Result of GPC analysis No No No No No No No No No No No Nopolymer polymer polymer polymer polymer polymer polymer polymer polymerpolymer polymer polymer formed formed formed formed formed formed formedformed formed formed formed formed

The symbols used in Table 1 are as follows.

As regards the vinyl ether group-containing (meth) acrylic esters, VEAstands for 2-vinyloxyethyl acrylate, VEM for 2-vinyloxyethylmethacrylate, VEEA for 2-(vinyloxyethoxy)ethyl acrylate, VEEM for2-(vinyloxyethoxy)ethyl methacrylate, VBA. for 4-vinyloxybutyl acrylate,and VBM for 4-vinyloxybutyl methacrylate. As regards the radicalpolymerization inhibitors, MEHQ stands for methoxyhydroquinone, PTZ forphenothiazine, HQ for hydroquinone, and TEMPO for2,2,6,6-tetramethylpiperidine-N-oxyl.

Example 13

A vinyl ether group-containing (meth) acrylic ester composition wasprepared by adding 5 mg of methoxyhydroquinone, a radical polymerizationinhibitor, and 5 mg of sodium hydroxide, a basic compound, to 100 g of2-vinyloxyethyl acrylate, and the composition was placed in a sealedcontainer and stored at 50° C. for 120 days. As results of analyses byvisual observation and GPC, neither discoloration nor high-molecularcompound formation was observed.

Examples 14 to 24

The same procedure as in Example 13 was followed except that the vinylether group-containing (meth) acrylic ester and/or radicalpolymerization inhibitor and/or basic compound used differed in speciesand/or the amounts thereof were varied. The species used, the amountsthereof and the results of visual observation and GPC are shown in Table2.

TABLE 2 Example 13 14 15 16 17 18 19 20 21 22 23 24 Vinyl ether VEA VEAVEM VEM VEEA VEEA VEEM VEEM VBA VBA VBM VBM group-containing (meth)acrylic ester (g) 100 100 100 100 100 100 100 100 100 100 100 100Radical MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQpolymerization inhibitor (mg)  5  5  5  5  5  5  5  5  5  5  5  5 BasicNaOH TEHA NaOH TEHA NaOH TEHA NaOH TEHA NaOH TEHA NaOH TEHA compound(mg)  5  5  5  5  5  5  5  5  5  5  5  5 Storage 50° C. 50° C. 50° C.50° C. 50° C. 50° C. 50° C. 50° C. 50° C. 50° C. 50° C. 50° C.temperature Number of 120 120 120 120 120 120 days 120 days 120 days 120days 120 days 120 days 120 days days of storage days days days days daysVisual No No No No No No change No change No change No change No changeNo change No change observation change change change change changeResult of No No No No No No No No No No No No GPC analysis polymerpolymer polymer polymer polymer polymer polymer polymer polymer polymerpolymer polymer formed formed formed formed formed formed formed formedformed formed formed formed

The symbols used in Table 2 are as follows.

As regards the basic compounds, NaOH stands for sodium hydroxide andTEHA for tris(2-ethylhexyl)amine. The other symbols are the same as inTable 1.

Comparative Examples 1 to 6

A 100-g portion of each of radical polymerization inhibitor-free vinylether group-containing (meth) acrylic ester was placed in a sealedcontainer and stored at 50° C. An hour later, all the vinyl ethergroup-containing (meth) acrylic esters used began to become turbid and,after 5 hours, became white solids insoluble in tetrahydrofuran. Thevinyl ether group-containing (meth) acrylic esters used were as shown inTable 3. The symbols used in Table 3 are the same as above.

TABLE 3 Comparative Example 1 2 3 4 5 6 Vinyl ether group-containing VEAVEM VEEA VEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100 100 100Radical polymerization inhibitor — — — — — — (mg) Basic compound — — — —— — (mg) Storage temperature 50° C. 50° C. 50° C. 50° C. 50° C. 50° C.Storage time 5 hrs 5 hrs 5 hrs 5 hrs 5 hrs 5 hrs Result THF-insolubleTHF-insoluble THF-insoluble THF-insoluble THF-insoluble THF-insolublesolid formed solid formed solid formed solid formed solid formed solidformed

Comparative Examples 7 and 8

The same procedures as in Comparative Example 1 was followed except thatradical polymerization inhibitor-free butyl methacrylate was used inComparative Example 7 and radical polymerization inhibitor-free2-(methoxyethoxy)ethyl methacrylate in Comparative Example 8. Butylmethacrylate and 2-(methoxyethoxy)ethyl methacrylate both showed noturbidity for 10 hours, without formation of any substance insoluble intetrahydrofuran.

Example 25

A vinyl ether group-containing (meth) acrylic ester composition wasprepared by adding 10 mg of methoxyhydroquinone, a radicalpolymerization inhibitor, to 100 g of 2-(vinyloxyethoxy)ethyl acrylate,and the composition was placed in a sealed container and stored at 100°C. for 12 hours. Until 5 hours later, no solid matter was detected byvisual observation. After 12 hours, however, the composition became asolid insoluble in tetrahydrofuran.

Example 26

The same procedure as in Example 25 was followed except that2-(vinyloxyethoxy)ethyl methacrylate was used in lieu of2-(vinyloxyethoxy)ethyl acrylate. Until 5 hours later, no solid matterwas detected by visual observation. After 12 hours, however, thecomposition became a solid insoluble in tetrahydrofuran.

Comparative Examples 9 and 10

The same procedure as in Example 25 was followed except that2-(methoxyethoxy)ethyl acrylate was used in Comparative Example 9 and2-(methoxyethoxy)ethyl methacrylate in Comparative Example 10. With both2-(methoxyethoxy)ethyl acrylate and 2-(methoxyethoxy)ethyl methacrylate,no tetrahydrofuran-insoluble matter formation was observed.

Example 27

The same procedure as in Example 13 was followed except that 100 g oftoluene was added following the production of the composition obtainedby Example 13. As results of analyses by visual observation and GPC,neither discoloration nor high-molecular compound formation wasobserved.

Example 28

The same procedure as in Example 13 was followed except that 50 g oftoluene was added following the production of the composition obtainedby Example 13. As results of analyses by visual observation and GPC,neither discoloration nor high-molecular compound formation wasobserved.

Example 29

The same procedure as in Example 13 was followed except that 25 g oftoluene was added following the production of the composition obtainedby Example 13. As results of analyses by visual observation and GPC,neither discoloration nor high-molecular compound formation wasobserved.

Example 30

The same procedure as in Example 13 was followed except that 10 g oftoluene was added following the production of the composition obtainedby Example 13. As results of analyses by visual observation and GPC,neither discoloration nor high-molecular compound formation wasobserved.

Example 31

The same procedure as in Example 13 was followed except that 5 g oftoluene was added following the production of the composition obtainedby Example 13. As results of analyses by visual observation and GPC,neither discoloration nor high-molecular compound formation wasobserved.

Each vinyl ether group-containing (meth) acrylic ester used in thefollowing Examples 32 to 55 was synthesized by the above-mentionedproduction method D and then purified by distillation under reducedpressure.

Example 32

A 100-g portion of 2-vinyloxyethyl acrylate having a water content of0.01% by weight as determined by using a model MKS 510 Karl Fischermoisture meter (product of Kyoto Denshi Kogyc, hereinafter referred toas “moisture meter”; indicator: Hydranal Composite 5K (product of R&HLaborchemikalien GmbH & Co. KG); solvent: Dehydrated Solvent KT (productof Mitsubishi Chemical)) was added to a test tube and 10 mg ofmethoxyhydroquinone was further added. After mixing, a 21% (by volume)oxygen gas (the balance being nitrogen) was passed through the gaseousphase in the test tube for 10 minutes and then the test tube was tightlystoppered.

The test tube prepared in the above manner was shaken on an oil bathmaintained at 80° C. for 40 days, followed by visual observation and byanalysis using a model GC-1700 gas chromatograph (product of Shimadzu;hereinafter this chromatographic analysis is referred to as “GC”, GPCand analysis using a model RQ Flex peroxide assaying instrument (productof Merck Co. Ltd.; hereinafter this analysis is referred to as “RQassay”). While neither impurity formation nor high-molecular substanceformation was observed, a peroxide content of 2 ppm was detected.

Examples 33 to 55

The same procedure as in Example 32 was repeated except that the vinylether group-containing (meth) acrylic ester and/or radicalpolymerization inhibitor used differed in species and/or the amountsthereof were varied and that the oxygen concentration and/or watercontent was varied and further that a basic compound was used or notused. The species used, the amounts thereof, the storage temperature,the number of days of storage, and the results of visual observation,GC, GPC and RQ assay are shown in Tables 4 to 6. The symbols used inTables 4 to 6 are the same as in Table 1 and Table 2.

TABLE 4 Example 32 33 34 35 36 37 38 39 Vinyl ether group-containing VEAVEM VEEA VEEA VEEM VEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100100 100 100 100 Radical polymerization inhibitor MEHQ MEHQ MEHQ MEHQMEHQ MEHQ MEHQ MEHQ (mg)  10  10  10  5  10  5  10  10 Basic compound —— — TEHA — TEHA — — (mg) — — —  5 —  5 — — Oxygen concentration 21 vol %21 vol % 21 vol % 21 vol % 21 vol % 21 vol % 21 vol % 21 vol % Watercontent 0.01 wt % 0.05 wt % 0.01 wt % 3 wt % 0.8 wt % 5 wt % 0.1 wt % 1wt % Storage temperature 80° C. 80° C. 80° C. 80° C. 80° C. 80° C. 80°C. 80° C. Number of days of storage 40 days 40 days 40 days 40 days 40days 40 days 40 days 40 days Visual observation No change No change Nochange No change No change No change No change No change Result of GCanalysis 1% purity 1% purity 1% purity 3% purity 2% purity 3% purity 2%purity 2% purity decrease decrease decrease decrease decrease decreasedecrease decrease Result of GPC analysis No polymer No polymer Nopolymer No polymer No polymer No polymer No polymer No polymer formedformed formed formed formed formed formed formed Result of RQ assay 2ppm 2 ppm 2 ppm 2 ppm 2 ppm 2 ppm 2 ppm 2 ppm

TABLE 5 Example 40 41 42 43 44 45 46 47 Vinyl ether group-containing VEAVEM VEEA VEEA VEEM VEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100100 100 100 100 Radical polymerization inhibitor MEHQ MEHQ MEHQ MEHQMEHQ MEHQ MEHQ MEHQ (mg)  10  10  10  5  10  5  10  10 Basic compound —— — TEHA — TEHA — — (mg) — — —  5 —  5 — — Oxygen concentration 1.5 vol% 0.8 vol % 5 vol % 10 vol % 7 vol % 9 vol % 7 vol % 0.5 vol % Watercontent 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % 7 wt % Storagetemperature 80° C. 80° C. 80° C. 80° C. 80° C. 80° C. 80° C. 80° C.Number of days of storage 40 days 40 days 40 days 40 days 40 days 40days 40 days 40 days Visual observation No change No change No change Nochange No change No change No change No change Result of GC analysis 3%purity 3% purity 3% purity 3% purity 3% purity 3% purity 3% purity 3%purity decrease decrease decrease decrease decrease decrease decreasedecrease Result of GPC analysis No polymer No polymer No polymer Nopolymer No polymer No polymer No polymer No polymer formed formed formedformed formed formed formed formed Result of RQ assay Not detected Notdetected Not detected Not detected Not detected Not detected Notdetected Not detected

TABLE 6 Example 48 49 50 51 52 53 54 55 Vinyl ether group-containing VEAVEM VEEA VEEA VEEM VEEM VBA VBM (meth) acrylic ester (g) 100 100 100 100100 100 100 100 Radical polymerization inhibitor MEHQ MEHQ MEHQ MEHQMEHQ MEHQ MEHQ MEHQ (mg)  10  10  10  5  10  5  10  10 Basic compound —— — TEHA — TEHA — — (mg) — — —  5 —  5 — — Oxygen concentration 7 vol %7 vol % 7 vol % 7 vol % 7 vol % 7 vol % 7 vol % 7 vol % Water content0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt % 0.01 wt %0.01 wt % Storage temperature 80° C. 80° C. 80° C. 80° C. 80° C. 80° C.80° C. 80° C. Number of days of storage 40 days 40 days 40 days 40 days40 days 40 days 40 days 40 days Visual observation No change No changeNo change No change No change No change No change No change Result of GCanalysis No change No change No change No change No change No change Nochange No change Result of GPC analysis No polymer No polymer No polymerNo polymer No polymer No polymer No polymer No polymer formed formedformed formed formed formed formed formed Result of RQ assay Notdetected Not detected Not detected Not detected Not detected Notdetected Not detected Not detected

Example 56

2-Vinyloxyethyl acrylate (100 g), 5 mg of methoxyhydroquinone and 5 mgof tris (2-ethylhexyl) amine were added to a 200-mL SUS 316 containerused as a lightproof structure. After mixing up, the gaseous phase inthe container was completely substituted with a 7% (by volume) oxygengas (the balance being nitrogen), followed by tight closure. Thecontainer was stored outdoors in an applicants' research laboratory atSuita, Osaka, Japan for 180 days starting from Apr. 1, 2000, followed byvisual observation, GC, GPC and RQ assay. No deterioration in qualitywas observed, namely neither impurity formation, nor high molecularsubstance formation nor peroxide formation was detected.

Examples 57 to 74

The same procedure as in Example 56 was repeated except that the vinylether group-containing (meth) acrylic ester and/or radicalpolymerization inhibitor and/or basic compound used differed in speciesand/or the amounts thereof were varied and the oxygen concentration wasvaried. The species used, the amounts thereof and the results of visualobservation, GC, GPC and RQ assay are shown in Table 7 and Table 8. Thesymbols used in Tables 7 and 8 are the same as in Tables 1 and 2.

TABLE 7 Example 56 57 58 59 60 61 62 63 64 Vinyl ether VEA VEA VEA VEMVEM VEM VEEA VEEA VEEA group-containing (meth) acrylic ester (g) 100 100100 100 100 100 100 100 100 Radical MEHQ MEHQ PTZ MEHQ PTZ MEHQ MEHQMEHQ PTZ polymerization inhibitor (mg)  5  10  10  5  10  10  5  10  10Basic TEHA — — TEHA — — TEHA — — compound (mg)  5 — —  5 — —  5 — —Oxygen 7 vol % 1 vol % 21 vol % 0.8 vol % 10 vol % 21 vol % 5 vol % 0.1vol % 21 vol % concentration Number of 180 days 180 days 180 days 180days 180 days 180 days 180 days 180 days 180 days days of storage VisualNo change No change No change No change No change No change No change Nochange No change observation Result of No change No change No change Nochange No change No change No change No change No change GC analysisResult of No polymer No polymer No polymer No polymer No polymer Nopolymer No polymer No polymer No polymer GPC analysis formed formedformed formed formed formed formed formed formed Result of Not detectedNot detected Not detected Not detected Not detected Not detected Notdetected Not detected Not detected RQ assay

TABLE 8 Example 65 66 67 68 69 70 71 72 73 74 Vinyl ethergroup-containing VEEM VEEM VEEM VEEM VBA VBA VBA VBM VBM VBM (meth)acrylic ester (g) 100 100 100 100 100 100 100 100 100 100 Radicalpolymerization MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQinhibitor (mg)  5  10  10  10  5  10  10  5  10  10 Basic compound TEHA— — — TEHA — — TEHA — — (mg)  5 — — —  5 — —  5 — — Oxygen concentration0.5 vol % 9 vol % 21 vol % 30 vol % 15 vol % 0.2 vol % 21 vol % 18 vol %0.3 vol % 21 vol % Number of days of storage 180 days 180 days 180 days180 days 180 days 180 days 180 days 180 days 180 days 180 days Visualobservation No change No change No change No change No change No changeNo change No change No change No change Result of GC analysis No changeNo change No change No change No change No change No change No change Nochange No change Result of GPC analysis No No No No No No No No No Nopolymer polymer polymer polymer polymer polymer polymer polymer polymerpolymer formed formed formed formed formed formed formed formed formedformed Result of RQ assay Not Not Not 10 ppm Not Not Not Not Not Notdetected detected detected detected detected detected detected detecteddetected

Example 75

The same procedure as in Example 56 was followed except that a 200-mLglass container coated with an opaque tetrafluoroethylene resin on 85%of the inside surface area thereof was used as a structure.

Upon GC, GPC and RQ assay, no deterioration in quality was observed,namely no impurity formation, no high-molecular substance formation orno peroxide formation was detected.

Comparative Example 11

The same procedure as in Example 56 was followed except that a 200-mLtransparent glass container was used as a structure.

As a result of visual observation, GC, GPC and RQ assay, impurityformation, the formation of a high-molecular substance with a molecularweight (number average) of 1,500 and peroxide formation (12 ppm) werefound.

Reference Example 1

The same procedure as in Comparative Example 11 was followed except that2-vinyloxyethyl propionate, which is the acryloyl group-free vinyl etherhaving similar structure as 2-vinyloxyethyl acrylate, was used in lieuof 2-vinyloxyethyl acrylate.

Reference Example 2

The same procedure as in Comparative Example 11 was followed except that2-ethoxyethyl acrylate, which is the vinyl ether group-free acrylateester having similar structure as 2-vinyloxyethyl acrylate, was used inlieu of 2-vinyloxyethyl acrylate.

In Reference Examples 1 and 2, each composition in the container after180 days of storage was evaluated by visual observation, GC, GPC and RQassay. No deterioration in quality was observed, namely neither impurityformation nor high-molecular substance formation nor peroxide formationwas detected.

According to the above results, it can be recognized that the vinylether group-containing (meth) acrylic esters have specific properties,which are not seen in either acryloyl group-free vinyl ethers havingsimilar structure or vinyl ether group-free acrylate esters havingsimilar structure.

Example 76

A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 529 g of 2-hydroxyethyl vinyl ethercontaining 11 g of ethylene glycol divinyl ether, 1,502 g of ethylacrylate, 300 mg of phenothiazine and 10 g of dioctyltin oxide. Thecontents were mixed and stirred while introducing air into the liquidphase from the gas inlet tube, and heating was started on an oil bathmaintained at 130° C. This was the production starting point. Thereaction was continued while continuously adding that amount of theacrylate ester corresponding to the weight of ethyl acrylate found inthe ethyl acrylate-ethanol azeotrope, namely the distillate at the topof the Oldershaw rectifying column, to the reaction system through theliquid addition line. Samples were taken from the reaction system at30-minute intervals from the production starting point and the yield ofthe desired 2-vinyloxyethyl acrylate was followed by GC. The yieldbecame constant after 8 hours. The production time was thus 8 hours. Theyield of 2-vinyloxyethyl acrylate at that time was 95 mole percent.

Examples 77 to 95

The same procedure as in Example 76 was repeated except that differentstarting materials, different impurities contained therein, differentpolymerization inhibitors and different catalysts were used. Thematerials used, the amounts thereof, the reaction time, the product andthe yield thereof as determined by GC for each run are shown in Table 9.In cases where methyl methacrylate was used as one of the startingmaterials, that weight of methyl methacrylate corresponding to themethyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line.

TABLE 9 Example 76 77 78 79 80 81 82 83 84 85 (Meth) acrylic ester AE AEAE MMA MMA MMA AE AE MMA MMA Amount charged (g) 1502 1502 1502 1502 15021502 1502 1502 1502 1502 OH-containing vinyl ether HEV HEV HEV HEV HEVHEV DEGV DEGV DEGV DEGV Amount charged (g) 528 529 529 529 529 529 793793 793 793 Impurity of formula (4) EGDV — EGDV EGDV — EGDV DEGDV DEGDVDEGDV — Content (g) 11 11 11 11 16 16 16 Impurity of formula (5) — MDOLMDOL — MDOL MDOL — MTOC — MTOC Content (g) 11 8 11 8 10 10 Impurity offormula (6) — — — — — — — — — — Content (g) Radical polymerization PTZPTZ PTZ PTZ PTZ PTZ MEHQ MEHQ MEHQ MEHQ inhibitor Amount added (mg) 300300 300 300 300 300 100 300 100 100 Radical polymerization — — — — — —TEMPOL TEMPOL PTZ inhibitor Amount added (mg) 20 20 200 Catalyst DOTODOTO DOTO DOTO DOTO DOTO DBTO DBTO DBTO DBTO Amount added (mg) 10 10 1010 10 10 8 8 8 8 Reaction time (hr) 8 8 7.5 8 8 7.5 8 7.5 8 8 ProductVEA VEA VEA VEM VEM VEM VEEA VEEA VEEM VEEM Yield (mol %) 95 95 95 96 9696 93 93 95 95 Example 86 87 88 89 90 91 92 93 94 95 (Meth) acrylicester MMA MMA MMA MMA AE AE AE MMA MMA MMA Amount charged (g) 1502 15021502 1502 1502 1502 1502 1502 1502 1502 OH-containing vinyl ether DEGVDEGV DEGV DEGV BDV BDV BDV BDV BDV BDV Amount charged (g) 793 793 793793 697 697 697 697 697 697 Impurity of formula (4) DEGDV DEGDV DEGDVDEGDV BDDV — — BDDV BDDV — Content (g) 16 16 16 16 14 14 14 Impurity offormula (5) — — — — — MDOP — — MDOP — Content (g) 12 11 Impurity offormula (6) — — — — — — 4BVE — — 4BVE Content (g) 16 16 Radicalpolymerization MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQinhibitor Amount added (mg) 100 300 100 20 200 200 200 200 200 200Radical polymerization TEMPOL TEMPOL TEMPOL TEMPO TEMPO TEMPO TEMPOTEMPO TEMPO inhibitor Amount added (mg) 20 20 50 100 100 100 100 100 100Catalyst TBT DBTDAc BDBTLO ZrAA DBTO DBTO DBTO DBTO DBTO DBTO Amountadded (mg) 5 10 10 5 8 8 8 8 8 8 Reaction time (hr) 8.5 8 8 5.5 8 8 8 87.5 8 Product VEEM VEEM VEEM VEEM VBA VBA VBA VBM VBM VBM Yield (mol %)94 92 93 99 94 94 94 95 95 95

The symbols used in Table 9 are as follows.

As regards the (meth) acrylic ester, AE stands for ethyl acrylate, andMMA for methyl methacrylate. As regards the hydroxyl group-containingvinyl ether, HEV stands for 2-hydroxyethyl vinyl ether, DEGVfordiethylene glycol monovinyl ether, and BDV for 1,4-butanediolmonovinyl ether. As regards the impurity of the general formula (4),namely the compound represented by the general formula (4) givenhereinabove, EGDV stands for ethylene glycol divinyl ether, DEGDV fordiethylene glycol divinyl ether, and BDDV for 1,4-butanediol divinylether. As regards the impurity of the general formula (5), namely thecompound represented by the general formula (5) given hereinabove, MDOLstands for 2-methyl-1,3-dioxolane, MTOC for 2-methyl-1,3,6-trioxocane,and MDOP for 2-methyl-1,3-dioxepane. As regards the impurity of thegeneral formula (6), namely the compound represented by the generalformula (6) given hereinabove, 4BVE stands for 4-butenyl vinyl ether. Asfor the radical polymerization inhibitor, TEMPOL stands for4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl. As regards thecatalyst, DBTO stands for dibutyltin oxide, DOTO for dioctyltin oxide,TBT for tetrabutoxytitanium, DBTDAc for dibutyltindiacetate, BDBTLO forbis(dibutyltin laurtae) oxide, and ZrAA for zirconia acetylacetonate.The other symbols are the same as in Table 1.

Example 96

The same apparatus as used in Example 76 was charged with 529 g of2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine, 10 g of dioctyltin oxide and 11 g of ethylene glycoldivinyl ether, and the same procedure as in Example 76 was carried out.As a result of following by GC, the production time was found to be 8hours, after which the yield of 2-vinyloxyethyl acrylate was 95 molepercent.

Example 97

The same apparatus as used in Example 76 was charged with 529 g of2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine and 10 g of dioctyltin oxide, and the reaction wasstarted, with stirring, by immersing the apparatus in an oil bath at130° C. The same procedure as in Example 76 was followed except that 11g of ethylene glycol divinyl ether was added 2 hours after the start. Asa result of following by GC, the production time was found to be 9hours, after which the yield of 2-vinyloxyethyl acrylate was 95 molepercent.

Comparative Examples 12 to 17

The same procedure as in Examples 76, 79, 82, 84, 90 or 93 was repeatedexcept that the hydroxyl group-containing vinyl ether used was free ofany impurity. The starting materials, polymerization inhibitor andcatalyst used, the amounts thereof, the production time found, theproduct and the yield thereof as determined by GC in each run are shownin Table 10. The symbols used in Table 10 are the same as in Table 9.

TABLE 10 Comparative Example 12 13 14 15 16 17 (Meth) acrylic ester AEMMA AE MMA AE MMA Amount charged (g) 1502 1502 1502 1502 1502 1502OH-containing vinyl ether HEV HEV DEGV DEGV BDV BDV Amount charged (g)529 529 793 793 697 697 Impurity of formula (4) — — — — — — Content (g)Impurity of formula (5) — — — — — — Content (g) Impurity of formula (6)— — — — — — Content (g) Radical polymerization inhibitor PTZ PTZ MEHQMEHQ MEHQ MEHQ Amount added (mg) 300 300 100 100 200 200 Radicalpolymerization inhibitor — — TEMPOL TEMPOL TEMPO TEMPO Amount added (mg)20 20 100 100 Catalyst DOTO DOTO DBTO DBTO DBTO DBTO Amount added (mg)10 10 8 8 8 8 Reaction time (hr) 12 11 13 12 12 13 Product VEA VEM VEEAVEEM VBA VBM Yield (mol %) 95 96 93 95 94 95

Example 98

A glass-made 3-liter five-necked flask was charged with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 529 g of 2-hydroxyethyl vinyl ether,1,502 g of ethyl acrylate, 300 mg of ohenothiazine and 10 g ofdibutyltin oxide.

On that occasion, the water content of the whole system as determined bythe moisture meter was 0.1% by weight. While introducing air into theliquid phase from the gas inlet tube, the contents were mixed andstirred and then temperature raising was started by immersing the flaskin an oil bath at 130° C. While continuously adding that amount of theacrylate ester corresponding to the weight of ethyl acrylate in theethyl acrylate-ethanol azeotrope distilling from the top of theOldershaw rectifying column to the reaction system through the liquidaddition line, the reaction was continued for 12 hours.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 95 mole percent. When 10 g of the reactionsystem was added to 100 mL of hexane, the system was dissolved to give acolorless transparent homogeneous solution.

Examples 99 to 108

The starting materials, polymerization inhibitor, basic compound andcatalyst used, the amounts thereof, the water content of the wholesystem as determine by using the moisture meter, the product and theyield thereof, and the result of the test for solubility in hexane areshown in Table 11 for each run. The symbols used in Table 11 are thesame as in Tables 1 to 10. In cases where methyl methacrylate was usedas one of the starting materials, that weight of methyl methacrylatecorresponding to the methyl methacrylate in the methylmethacrylate-methanol azeotrope distillate was continuously added toreaction system through the liquid addition line.

TABLE 11 Example 98 99 100 101 102 103 104 105 106 107 108 (Meth) AE MMAAE MMA MMA MMA MMA MMA MMA AE MMA acrylic ester Amount 1502 1502 15021502 1502 1502 1502 1502 1502 1502 1502 charged (g) OH-containing HEVHEV DEGV DEGV DEGV DEGV DEGV DEGV DEGV BDV BDV vinyl ether Amount 529529 793 793 793 793 793 793 793 697 697 charged (g) Radical PTZ PTZ MEHQMEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ MEHQ polymerization inhibitor Amount300 300 300 300 300 300 300 300 300 300 300 added (mg) Basic — — — —NaOH — — — — — — compound Amount 100 added (mg) Catalyst DBTO DBTO DBTODBTO DBTO TBT DBTDAc BDBTLO ZrAA DBTO DBTO Amount 10 10 10 10 10 10 1010 10 10 10 added (mg) Water 0.1 0.1 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1content (wt %) Product VEA VEM VEEA VEEM VEEM VEEM VEEM VEEM VEEM VBAVBM Yield (mol %) 95 96 93 95 95 94 92 93 99 94 95 Solubility inColorless, Colorless, Colorless, Colorless, Colorless, Colorless,Colorless, Colorless, Colorless, Colorless, Colorless, hexane clearclear clear clear clear clear clear clear clear clear clear

Comparative Examples 18 to 23

The starting materials, polymerization inhibitor, basic compound andcatalyst used, the amounts thereof, the water content of the wholesystem as determine by using the moisture meter, the product and theyield thereof, and the result of the test for solubility in hexane areshown in Table 12 for each run. The symbols used in Table 12 are thesame as in Tables 1 to 10.

TABLE 12 Comparative Example 18 19 20 21 22 23 (Meth) acrylic ester AEMMA AE MMA AE MMA Amount charged (g) 1502 1502 1502 1502 1502 1502OH-containing vinyl ether HEV HEV DEGV DEGV DEGV DEGV Amount charged (g)529 529 793 793 793 793 Radical polymerization inhibitor PTZ PTZ MEHQMEHQ MEHQ MEHQ Amount added (mg) 300 300 300 300 300 300 Catalyst DBTODBTO DBTO DBTO DBTO TBT Amount added (mg) 10 10 10 10 10 10 Watercontent (wt %) 6.0 6.0 6.0 6.0 5.5 5.5 Product VEA VEM VEEA VEEM VEEMVEEM Yield (mol %) 93 94 89 91 92 90 Solubility in hexane Slightlyturbid Slightly turbid Slightly turbid Slightly turbid Slightly turbidSlightly turbid

Example 109

A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 529 g of 2-hydroxyethyl vinyl ether,1,502 g of ethyl acrylate, 300 mg of phenothiazine and 10 g ofdibutyltin oxide. The contents were mixed and stirred while introducingan 8% (by volume) oxygen gas (the balance being nitrogen) into theliquid phase from the gas inlet tube, and heating was started on an oilbath maintained at 130° C. The reaction was continued for 12 hours whilecontinuously adding that amount of the ethyl acrylate corresponding tothe weight of the ethyl acrylate found in the ethyl acrylate-ethanolazeotrope, namely the distillate at the top of the Oldershaw rectifyingcolumn, to the reaction system through the liquid addition line. Themolecular oxygen concentration in the gaseous phase during reaction was0.1 to 8% by volume. As a result of analysis by GC, the yield of thedesired 2-vinyloxyethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system. As a result of analysis of theliquid phase by RQ assay, no peroxide was detected.

Example 110

The same procedure as in Example 109 was followed except that a 8% (byvolume) oxygen gas (the balance being nitrogen) was introduced into thegaseous phase. The molecular oxygen concentration in the gaseous phaseduring reaction was 0.1 to 8% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or in the liquid phase of the reactionsystem. As a result of analysis of the liquid phase by RQ assay, noperoxide was detected.

Examples 111 to 116

The same procedure as in Example 109 was repeated except that the (meth)acrylic ester and/or hydroxyl group-containing vinyl ether and/orradical polymerization inhibitor used differed in species and/or theamounts thereof were varied and that the oxygen concentration was variedand further that a basic compound was used or not used. The speciesused, the amounts thereof, the vinyl ether group-containing (meth)acrylic ester produced and the yield thereof, the molecular oxygenconcentration in the gaseous phase during reaction, and the absence orpresence of a solid matter in the gaseous phase and in the liquid phaseof the reaction system and the result of analysis by RQ assay are shownfor each run in Table 13. The symbols used in Table 13 are the same asin Tables 1 to 12.

In cases where methyl methacrylate was used as one of the startingmaterials, that weight of methyl methacrylate corresponding to themethyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line.

TABLE 13 Example 111 112 113 114 115 116 (Meth) acrylic ester AE MMA AEMMA AE MMA Amount charged (g) 1502 1502 1502 1502 1502 1502OH-containing vinyl ether HEV HEV DEGV DEGV BDV BDV Amount charged (g)529 529 793 793 697 697 Radical polymerization inhibitor PTZ MEHQ PTZMEHQ PTZ MEHQ Amount added (mg) 300 300 300 300 300 300 Basic compoundNaOH — NaOH — NaOH — Amount added (mg) 100 100 100 Catalyst DBTO DBTODBTO DBTO DBTO DBTO Amount added (mg) 10 10 10 10 10 10 Oxygenconcentration (vol %) 6 10 2 0.5 5 7 Molecular oxygen concentration ingaseous 0.05~6 0.1~10 0.03~2 0.02~0.5 0.08~5 0.1~7 phase during reaction(vol %) Product VEA VEM VEEA VEEM VBA VBM Yield (mol %) 96 97 93 95 9495 Solid matter formation in liquid phase No No No No No No Solid matterformation in gaseous phase No No No No No No Result of RQ assay Notdetected Not detected Not detected Not detected Not detected Notdetected

Example 117

A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column and liquid addition line wascharged with 793 g of diethylene glycol monovinyl ether, 1,502 g ofethyl acrylate, 300 mg of phenothiazine, 300 mg of AluminumN-nitrosophenylhydroxylamine and 10 g of dioctyltin oxide. While mixingand stirring, the flask was immersed in an oil bath maintained at 130°C., and the temperature was allowed to begin to rise. The reaction wascontinued for 12 hours while continuously adding that amount of ethylacrylate corresponding to the weight of the ethyl acrylate found in theethyl acrylate-ethanol azeotrope, namely the distillate at the top ofthe Oldershaw rectifying column, to the reaction system through theliquid addition line. As a result of analysis by GC, the yield of thedesired 2-(vinyloxyethoxy)ethyl acrylate was found to be 95 molepercent. No solid matter formation was found either in the gaseous phaseor in the liquid phase of the reaction system.

Example 118

The same procedure as in Example 117 was followed except that 1,502 g ofmethyl methacrylate was used in lieu of ethyl acrylate.

As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy)ethyl methacrylate was found to be 97 mole percent Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Example 119

A glass-made 3-liter five-necked flask equipped with a stirrer,thermometer, Oldershaw rectifying column, gas inlet tube and liquidaddition line was charged with 793 g of diethylene glycol monovinylether, 1,502 g of ethyl acrylate, 300 mg of phenothiazine and 10 g ofdioctyltin oxide. The contents were mixed and stirred while introducingan 8% (by volume) nitrogen monoxide gas (the balance being nitrogen)into the liquid phase from the gas inlet tube, and heating was startedon an oil bath maintained at 130° C. The reaction was continued for 12hours while continuously adding that amount of ethyl acrylatecorresponding to the weight of the ethyl acrylate found in the ethylacrylate-ethanol azeotrope, namely the distillate at the top of theOldershaw rectifying column, to the reaction system through the liquidaddition line.

The nitrogen monoxide gas concentration in the gaseous phase duringreaction was 0.1 to 8% by volume.

As a result of analysis by GC, the yield of the desired2-vinyloxyethoxy)ethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Example 120

The same procedure as in Example 109 was followed except that an 8% (byvolume) nitrogen monoxide gas (the balance being nitrogen) wasintroduced into the gaseous phase. The molecular nitrogen monooxideconcentration in the gaseous phase during reaction was 0.1 to 8% byvolume.

As a result of analysis by GC, the yield of the desired2-vinyloxyethoxy)ethyl acrylate was found to be 96 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Example 121

The same procedure as in Example 119 was followed except that 1,502 g ofmethyl methacrylate was used in lieu of ethyl acrylate. The molecularnitrogen monooxide concentration in the gaseous phase during reactionwas 0.1 to 8% by volume.

As a result of analysis by GC, the yield of the desired2-(vinyloxyethoxy)ethyl methacrylate was found to be 97 mole percent. Nosolid matter formation was found either in the gaseous phase or in theliquid phase of the reaction system.

Comparative Example 24

The same procedure as in Example 109 was followed without introducingthe 8% (by volume) oxygen gas (the balance being nitrogen) After 2hours, a white solid was formed in the gaseous phase and liquid phaseand, therefore, the reaction was discontinued.

Example 122

A lightproof structure, namely a 3-liter separable to apparatus made ofSUS 316 and equipped with a stirrer, thermometer holder, gas inlet tube,liquid addition line and rectifying column was charged with 529 g of2-hydroxyethyl vinyl ether, 1,502 g of ethyl acrylate, 300 mg ofphenothiazine and 10 g of dibutyltin oxide. The contents were mixed andstirred while introducing air into the liquid phase from the gas inlettube, and heating was started on an oil bath maintained at 130° C. Thereaction was continued for 12 hours while continuously adding thatamount of ethyl acrylate corresponding to the weight of the ethylacrylate found in the ethyl acrylate-ethanol azeotrope, namely thedistillate at the top of the Oldershaw rectifying column, to thereaction system through the liquid addition line.

The molecular oxygen concentration in the gaseous phase during reactionwas 0.1 to 21% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or in the liquid phase of the reactionsystem. As a result of analysis of the liquid phase by RQ assay, 3 ppmof peroxide was detected.

Example 123

The same procedure as in Example 122 was followed except that a 15% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof air. The molecular oxygen concentration in the gaseous phase duringreaction was 0.1 to 15% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or in the liquid phase of the reactionsystem. As a result of analysis by RQ assay, no peroxide was detected.

Examples 124 to 131

The same procedure as in Example 123 was repeated except that the (meth)acrylic ester and/or hydroxyl group-containing vinyl ether and/orradical polymerization inhibitor used differed in species and/or theamounts thereof were varied and that the oxygen concentration was variedand further that a basic compound was used or not used. The speciesused, the amounts thereof, the vinyl ether group-containing (methacrylic ester produced and the yield thereof, the molecular oxygenconcentration in the gaseous phase during reaction, and the absence orpresence of a solid matter in the gaseous phase and in the liquid phaseof the reaction system and the result of analysis by RQ assay are shownfor each run in Table 14. The symbols used in Table 14 are the same asin Tables 1 to 13.

In cases where methyl methacrylate was used as one of the startingmaterials, that weight of methyl methacrylate corresponding to themethyl methacrylate in the methyl methacrylate-methanol azeotropedistillate was continuously added to reaction system through the liquidaddition line.

TABLE 14 Example 124 125 126 127 128 129 130 131 (Meth) acrylic ester AEMMA AE AE MMA MMA AE MMA Amount charged (g) 1502 1502 1502 1502 15021502 1502 1502 OH-containing vinyl ether HEV HEV DEGV DEGV DEGV DEGV BDVBDV Amount charged (g) 529 529 793 793 793 793 697 697 Radicalpolymerization inhibitor MEHQ PTZ TEMPO MEHQ PTZ MEHQ MEHQ TEMPO Amountadded (mg) 200 300 300 250 300 200 300 300 Basic compound TEHA — — NaOH— TEHA NaOH — Amount added (mg) 100 100 100 80 Catalyst DBTO DBTO DBTODBTO DBTO DBTO DBTO DBTO Amount added (mg) 10 10 10 10 10 10 10 10Oxygen concentration (vol %) 7 10 8 5 0.5 0.2 1 2 Molecular oxygenconcentration 0.1~7 0.1~10 0.1~8 0.1~5 0.1~0.5 0.1~0.2 0.1~1 0.1~2 ingaseous phase during reaction (vol %) Product VEA VEM VEEA VEEA VEEMVEEM VBA VBM Yield (mol %) 96 97 93 93 95 95 94 95 Solid matterformation in liquid No No No No No No No No phase Solid matter formationin No No No No No No No No gaseous phase Result of RQ assay Not detectedNot detected Not detected Not detected Not detected Not detected Notdetected Not detected

Example 132

The same procedure as in Example 123 was followed except that the upperlid-forming portion of the SUS 316-made separable apparatus used inExample 123 was replaced with a transparent glass lid (in this case, thelightproof material SUS 316 accounted for 83% of the reaction apparatusstructure inside surface area otherwise through which light could reachwithin the structure inside). The molecular oxygen concentration in thegaseous phase during reaction was 0.1 to 15% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or-in the liquid phase of the reactionsystem. As a result of analysis by RQ assay, no peroxide was detected.

Comparative Example 25

The same procedure as in Example 109 was followed except that air wasintroduced in lieu of the 8% (by weight) oxygen gas (the balance beingnitrogen). The molecular oxygen concentration in the gaseous phaseduring reaction was 0.1 to 21% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or in the liquid phase of the reactionsystem. As a result of analysis by RQ assay, however, 17 ppm of peroxidewas detected.

Comparative Example 26

The same procedure as in Example 109 was followed except that a 15% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by weight) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during reaction was0.1 to 15% by volume.

As a result of analysis by GC, the yield of the desired 2-vinyloxyethylacrylate was found to be 96 mole percent. No solid matter formation wasfound either in the gaseous phase or in the liquid phase of the reactionsystem. As a result of analysis by RQ assay, however, 12 ppm of peroxidewas detected.

Example 133 Raw Material Recovery Procedure

The reaction mixture obtained by the same procedure as in Example 127was introduced into a glass-made 3-liter distillation apparatus equippedwith a stirrer, thermometer holder, gas inlet tube, pressure reducingregulator and rectifying column. While introducing an 8% (by volume)oxygen gas (the balance being nitrogen) into the liquid phase, thecontents were mixed and stirred and heating was started on an oil bathmaintained at 130° C. By reducing the pressure gradually from 667 hPa to67 hPa, ethyl acrylate and ethanol were allowed to distill out of thetop of the rectifying column and the starting material ethyl acrylatewas recovered. The molecular oxygen concentration in the gaseous phaseduring raw material recovery procedure was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 134 Raw Material Recovery Procedure

The same procedure as in Example 133 was followed except that a 10% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.1 to 10% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 135 Raw Material Recovery Procedure

The same procedure as in Example 133 was followed except that a 0.1% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.02 to 0.1% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 136 Raw Material Recovery Procedure

The same procedure as in Example 133 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127. Methyl methacrylate and methanol were thusallowed to distill out of the top of the rectifying column and thestarting material methyl methacrylate was recovered. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 137 Raw Material Recovery Procedure

Following the procedure of Example 133, the contents in the apparatuswere mixed and stirred while introducing an 8% (by volume) oxygen gas(the balance being nitrogen) into the liquid phase, and the temperaturewas raised on an oil bath at 150° C. By reducing the pressure to 17 hPa,that portion of the starting material diethylene glycol monovinyl etherremaining unreacted was caused to distill off from the top of therectifying column and thus recovered. The molecular oxygen concentrationin the gaseous phase during raw material recovery procedure was 0.1to—by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no, peroxide was detected.

Example 138 Raw Material Recovery Procedure

Following the procedure of Example 136, the same procedure as in Example137 was followed. The molecular oxygen concentration in the gaseousphase during raw material recovery procedure was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 139 Distillation/Purification Procedure

The mixture obtained by the same procedure as in Example 137 wasintroduced into a glass-made one-liter distillation apparatus equippedwith a stirrer, thermometer holder, gas inlet tube, pressure reducingregulator and rectifying column. While introducing an 8% (by volume)oxygen gas (the balance being nitrogen) into the liquid phase from thegas inlet tube, the contents were mixed and stirred and heating wasstarted on an oil bath maintained at 150° C. By reducing the pressuregradually to 13 hPa, 2-(vinyloxyethoxy)ethyl acrylate was caused todistill off from the top of the rectifying column for purifying thesame. The molecular oxygen concentration in the gaseous phase duringdistillation/purification was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis by RQ assay of the liquid phase and of the distillate2-(vinyloxyethoxy)ethyl acrylate, no peroxide was detected.

Example 140 Distillation/Purification Procedure

The same procedure as in Example 139 was followed except that themixture obtained by the same procedure as in Example 138 was introducedin lieu of the mixture obtained by the same procedure as in Example 137,to thereby causing 2-(vinyloxyethoxy)ethyl methacrylate to distill outfor purifying the same. The molecular oxygen concentration in thegaseous phase during distillation/purification was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis by RQ assay of the liquid phase and of the distillate2-(vinyloxyethoxy)ethyl methacrylate, no peroxide was detected.

Example 141 Water Washing Procedure

A 400-mL portion of the reaction mixture obtained by the same procedureas in Example 127 was introduced, together with 400 mL of a 1 N aqueoussolution of sodium hydroxide, into a glass-made one-liter separatingapparatus equipped with a stirrer and a gas inlet tube. Whileintroducing an 8% (by volume) oxygen gas (the balance being nitrogen)into the gaseous phase from the gas inlet tube, the contents werestirred at room temperature for 1 hour, and then the contents wereallowed to stand for 1 hour, whereby they separated into an oil phase,an aqueous phase and a catalyst phase. After removing the aqueous phasecontaining unreacted diethylene glycol monovinyl ether, the catalystphase was removed by filtration.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the separating apparatus. Furthermore, as a resultof analysis of the oily phase by RQ assay, no peroxide was detected.

Example 142 Water Washing Procedure

The same procedure as in Example 141 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby remove the aqueous phasecontaining unreacted diethylene glycol monovinyl ether and the catalystlayer.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the separating apparatus. Furthermore, as a resultof analysis of the oil phase by RQ assay, no peroxide was detected.

Example 143 Raw Material Recovery Procedure

The reaction mixture obtained by the same procedure as in Example 127was introduced into a lightproof structure, namely a SUS 316-made3-liter distillation apparatus equipped with a stirrer, thermometerholder, gas inlet tube, pressure reduction regulator and rectifyingcolumn. While introducing a 15% (by volume) oxygen gas (the balancebeing nitrogen) into the liquid phase through the gas inlet tube, thecontents were mixed and stirred, and heating was started on an oil bathat 130° C. By reducing the pressure gradually from 667 hPa to 67 hPa,ethyl acrylate and ethanol were allowed to distill out of the top of therectifying column and thus the starting material ethyl acrylate wasrecovered. The molecular oxygen concentration in the gaseous phaseduring raw material recovery procedure was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 144 Raw Material Recovery Procedure

The same procedure as in Example 143 was followed except 35 that an 8%(by volume) oxygen gas (the balance being nitrogen) was introduced inlieu of the 15% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.1 to 8% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 145 Raw Material Recovery Procedure

The same procedure as in Example 143 was followed except that a 0.1% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 15% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.02 to 0.1% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 146 Raw Material Recovery Procedure

The same procedure as in Example 143 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby cause methyl methacrylate andmethanol to distill out of the top of the rectifying column forrecovering the starting material methyl methacrylate. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, no peroxide was detected.

Example 147 Raw Material Recovery Procedure

Following the procedure of Example 143, the residue was stirred whileintroducing a 15% (by volume) oxygen gas (the balance being nitrogen)into the liquid phase, and heating was started on an oil bath at 150° C.By reducing the pressure to 17 hPa, the unreacted portion of thestarting material diethylene glycol monovinyl ether was distilled out ofthe top of the rectifying column for recovering the same. The molecularoxygen concentration in the gaseous phase during raw material recoveryprocedure was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ 15 assay, no peroxide wasdetected.

Example 148 Raw Material Recovery Procedure

Following the procedure of Example 146, the same procedure as in Example147 was followed. The molecular oxygen concentration in the gaseousphase during raw material recovery procedure was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis by RQ assay of the liquid 25 phase, no peroxide wasdetected.

Comparative Example 27 Raw Material Recovery Procedure

The same procedure as in Example 133 was followed except that a 15% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase during raw materialrecovery procedure was 0.1 to 15% by volume.

No solid matter formation was observed either in the 35 gaseous phase orin the liquid phase of the distillation apparatus. Furthermore, as aresult of analysis by RQ assay of the liquid phase, L2 ppm of peroxidewas detected.

Example 149 Distillation/Purification Procedure

The mixture obtained by the same procedure as in Example 147 wasintroduced into a lightproof structure, namely a SUS 316-made one-literdistillation apparatus equipped with a stirrer, thermometer holder, gasinlet tube, pressure reduction regulator and rectifying column. Whileintroducing a 15% (by volume) oxygen gas (the balance being nitrogen)into the liquid phase through the gas inlet tube, the contents weremixed and stirred, and heating was started on an oil bath at 150° C. Byreducing the pressure to 13 hPa, 2-(vinyloxyethoxy)ethyl acrylate wasallowed to distill out of the top of the rectifying column and the samewas thus purified. The molecular oxygen concentration in the gaseousphase during distillation/purification was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis by RQ assay of the liquid phase and of the distillate2-(vinyloxyethoxy)ethyl acrylate, no peroxide was detected.

Example 150 Distillation/Purification Procedure

The same procedure as in Example 149 was followed except that themixture obtained by the same procedure as in Example 148 was introducedin lieu of the mixture obtained by the same procedure as in Example 147,to thereby cause 2-(vinyloxyethoxy)ethyl methacrylate to distill out forpurifying the same. The molecular oxygen concentration in the gaseousphase during distillation/purification was 0.1 to 15% by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. 35 Furthermore, as aresult of analysis by RQ assay of the liquid phase and of the distillate2-(vinyloxyethoxy)ethyl methacrylate, no peroxide was detected.

Comparative Example 28 Distillation/Purification Procedure

The same procedure as in Example 139 was followed except that a 15% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by volume) oxygen gas (the balance being nitrogen). Themolecular oxygen concentration in the gaseous phase duringdistillation/purification was 0.1 to 131 by volume.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the distillation apparatus. Furthermore, as a resultof analysis of the liquid phase by RQ assay, 21 ppm of peroxide wasdetected.

Example 151 Water Washing Procedure

A 400-mL portion of the reaction mixture obtained by the same procedureas in Example 127 was introduced, together with 400 mL of a 1 N aqueoussolution of sodium hydroxide, into a lightproof structure, namely aSUS136-made one-liter separating apparatus equipped with a stirrer and agas inlet tube. While introducing a 15% (by volume) oxygen gas (thebalance being nitrogen) into the gaseous phase, the contents werestirred at room temperature for 1 hour, and then the contents wereallowed to stand for 1 hour, whereby they separated into an oil phase,an aqueous phase and a catalyst phase. After removing the aqueous phasecontaining unreacted diethylene glycol monovinyl ether, the catalystphase was removed by filtration.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the separating apparatus. Furthermore, as a resultof analysis of the oily phase by RQ assay, no peroxide was detected.

Example 152 Water Washing Procedure

The same procedure as in Example 151 was followed except that thereaction mixture obtained by the same procedure as in Example 129 wasintroduced in lieu of the reaction mixture obtained by the sameprocedure as in Example 127, to thereby remove The aqueous phasecontaining unreacted diethylene glycol monovinyl ether and the catalystlayer.

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the separating apparatus. Furthermore, as a resultof analysis of the oily phase by RQ assay, no peroxide was detected.

Comparative Example 29 Water Washing Procedure

The same procedure as in Example 141 was followed except that a 15% (byvolume) oxygen gas (the balance being nitrogen) was introduced in lieuof the 8% (by volume) oxygen gas (the balance being nitrogen).

No solid matter formation was observed either in the gaseous phase or inthe liquid phase of the separating apparatus. However, as a result ofanalysis of the oily phase by RQ assay, 10 ppm of peroxide was detected.

1-17. (canceled)
 18. A method of transporting, storing or transferring avinyl ether group-containing (meth)acrylic ester, which comprisestransporting, storing or transferring said vinyl ether group-containing(meth)acrylic ester under the condition such that said vinyl ethergroup-containing (meth)acrylic ester is placed in a container and amolecular oxygen concentration in the gaseous phase in the container is0.01 to 15% by volume and said vinyl ether group-containing(meth)acrylic ester being represented by the following formula (1):CH₂═CR¹—COO—R²—O—CH═CH—R³  (1) in the formula, R¹ represents a hydrogenatom or a methyl group, R² represents a straight, branched or cyclicalkylene group containing 2 to 20 carbon atoms, an alkylene groupcontaining 2 to 20 carbon atoms and having at least one oxygen atom inthe form of an ether linkage and/or an ester linkage within thestructure thereof, or an aromatic group which contains 6 to 11 carbonatoms and may optionally be substituted, and R³ represents a hydrogenatom, a straight, branched or cyclic alkyl group containing 1 to 10carbon atoms, or an aromatic group which contains 6 to 11 carbon atomsand may optionally be substituted.
 19. A method of producing a vinylether group-containing (meth)acrylic ester represented by the followingformula (1):CH₂═CR¹—COO—R²—O—CH═CH—R³  (1) in the formula, R¹ represents a hydrogenatom or a methyl group, R² represents a straight, branched or cyclicalkylene group containing 2 to 20 carbon atoms, an alkylene groupcontaining 2 to 20 carbon atoms and having at least one oxygen atom inthe form of an ether linkage and/or an ester linkage within thestructure thereof, or an aromatic group which contains 6 to 11 carbonatoms and may optionally be substituted, and R³ represents a hydrogenatom, a straight, branched or cyclic alkyl group containing 1 to 10carbon atoms, or an aromatic group which contains 6 to 11 carbon atomsand may optionally be substituted, which comprises reacting a hydroxylgroup-containing vinyl ether represented by the following formula (2):R³—CH═CH—O—R²—OH  (2) in the formula, R² represents a straight, branchedor cyclic alkylene group containing 2 to 20 carbon atoms, an alkylenegroup containing 2 to 20 carbon atoms and having at least one oxygenatom in the form of an ether linkage and/or an ester linkage within thestructure thereof, or an aromatic group which contains 6 to 11 carbonatoms and may optionally be substituted, and R³ represents a hydrogenatom, a straight, branched or cyclic alkyl group containing 1 to 10carbon atoms, or an aromatic group which contains 6 to 11 carbon atomsand may optionally be substituted, with a (meth)acrylic esterrepresented by the following formula (3):CH₂═CR¹—COOR⁴  (3) in the formula, R¹ represents a hydrogen atom or amethyl group and R⁴ represents a straight, branched a cyclic alkyl groupcontaining 1 to 8 carbon atoms, in an atmosphere such that a molecularoxygen concentration is 0.01 to 10% by volume.
 20. A method oftransporting, storing or transferring a vinyl ether group-containing(meth)acrylic ester which comprises transporting, storing ortransferring said vinyl ether group-containing (meth)acrylic ester in alightproof structure while keeping a molecular oxygen concentration inthe gaseous phase within said lightproof structure at 0.01 to 22% byvolume and said vinyl ether group-containing (meth)acrylic ester beingrepresented by the following formula (1):CH₂═CR¹—COO—R²—O—CH═CH—R³  (1) in the formula, R¹ represents a hydrogenatom or a methyl group, R² represents a straight, branched or cyclicalkylene group containing 2 to 20 carbon atoms, an alkylene groupcontaining 2 to 20 carbon atoms and having at least one oxygen atom inthe form of an ether linkage and/or an ester linkage within thestructure thereof, or an aromatic group which contains 6 to 11 carbonatoms and may optionally be substituted, R³ represents a hydrogen atom,a straight, branched or cyclic alkyl group containing 1 to 10 carbonatoms, or an aromatic group which contains 6 to 11 carbon atoms and mayoptionally be substituted.